KR102523153B1 - Motor drive apparatus performing algorithm for preventing abnormal operation - Google Patents

Abstract

The present invention relates to a motor driving device that performs an algorithm capable of preventing abnormal operation due to unstable power. The motor driving device according to the present invention includes an inverter that converts an input DC voltage into an AC voltage and provides it to the motor, and a control applied to the inverter based on detecting a time when the DC voltage is maintained smaller than a reference voltage. By including a control unit that cuts off the signal, it is possible to prevent generation of peak current due to an abnormal power input and secure stability of motor control.

Description

Motor drive apparatus performing algorithm for preventing abnormal operation}

The present invention relates to a motor driving device that performs an algorithm capable of preventing abnormal operation due to unstable power input.

Small precision control motors are largely classified into AC motors, DC motors, brushless DC motors, and reluctance motors.

These small precision control motors are used in many places, such as for AV devices, computers, home appliances and housing facilities, and industrial use. In particular, the home appliance field is forming the largest market for small motors. Home appliances are gradually becoming more sophisticated, and accordingly, miniaturization, low noise, low consumption, and power consumption of driven motors are required.

Among them, a BLDC motor (Brushless Direct Current motor) is a motor without brushes and commutators. Mechanical friction loss, sparks, and noise do not occur in principle, and speed control and torque control are excellent. In addition, there is no loss due to speed control, and as a small motor, it is widely used in products in the field of home appliances due to its high efficiency.

The BLCD motor may include an inverter providing a three-phase AC voltage and a control unit controlling an output voltage of the inverter. At this time, the control unit may control the inverter using a PWM control method.

Recently, in order to secure price competitiveness of inverters, there is a tendency to develop capless products in which a capacitor connected to a power terminal of a DC link applied to an inverter is reduced in size or removed.

When an unintentional power cutoff occurs while using such a capless product, the inverter operates with no input voltage, but continues to perform a control operation while power is supplied to each other element.

At this time, since a state in which the target value and the current value of the motor do not match continues in the control unit controlling the inverter, a situation in which the command value inside the control unit continues to increase occurs. Accordingly, since the command value increased by the regenerative voltage of the motor is directly reflected in the control signal of the motor, a peak current may be instantaneously generated.

When such a peak current is generated, component burnout may occur in the peripheral circuit (for example, an inverter or control circuit), and the temperature of the motor rises abnormally, causing a problem in which the coil may ignite or the bearing may be damaged. there is.

SUMMARY OF THE INVENTION An object of the present invention is to provide a motor driving device capable of securing stability of motor control by detecting whether or not abnormal power is applied to an inverter and stopping the start of the motor based on this.

Another object of the present invention is to provide a motor driving device capable of preventing component burnout in an abnormal situation in which input power applied to an inverter is cut off.

Another object of the present invention is to provide a motor driving device capable of reliably restarting a motor when input power applied to an inverter is restored to normal.

The objects of the present invention are not limited to the above-mentioned objects, and other objects and advantages of the present invention not mentioned above can be understood by the following description and will be more clearly understood by the examples of the present invention. It will also be readily apparent that the objects and advantages of the present invention may be realized by means of the instrumentalities and combinations indicated in the claims.

A motor driving apparatus according to the present invention includes an inverter that converts an input DC voltage into an AC voltage and provides it to a motor, detects a time when the DC voltage is maintained smaller than a reference voltage, and applies a control signal to the inverter based on this. By including a control unit that cuts off, it is possible to prevent the occurrence of abnormal peak current and secure the stability of motor control.

In addition, the motor driving apparatus according to the present invention includes a motor including a rotor rotating by a magnetic field generated from a three-phase coil, an inverter controlling the operation of three-phase switch elements, and a DC voltage applied to the inverter as a reference voltage. By including a control unit that cuts off the control signal applied to the inverter based on the time remaining smaller, it is possible to prevent burnout of the motor and other components due to an abnormal peak current.

In addition, the motor driving apparatus according to the present invention includes a control unit that provides a control signal to the inverter again when the magnitude of the DC voltage applied to the inverter is greater than the magnitude of the reference voltage, thereby stably restarting the motor. can

The motor driving apparatus according to the present invention detects whether or not abnormal power is applied to the inverter and stops the start of the motor based on this, thereby preventing abnormal peak current from occurring and ensuring stability of motor control. In addition, the generation of abnormal peak current can be prevented only by changing the algorithm of the control unit without adding a separate abnormal current detection device, thereby reducing the unit cost of motor production and maximizing corporate profits.

In addition, the motor driving device according to the present invention can prevent burnout of the motor and other parts due to an abnormal peak current or a fire due to abnormal peak current in an abnormal situation in which input power applied to the inverter is cut off.

In addition, the motor driving device according to the present invention, when the input power applied to the inverter is restored to normal, restarts the motor stably so that the system can be automatically restored after the occurrence of temporary input power abnormality is resolved. . Through this, the convenience of the manager and the stability of the system can be improved.

In addition to the effects described above, specific effects of the present invention will be described together while explaining specific details for carrying out the present invention.

1 is a block diagram showing a motor driving device according to an embodiment of the present invention.
FIG. 2 is a circuit diagram illustrating a voltage detection unit of FIG. 1 .
Figure 3 is a block diagram showing the components of the control unit of Figure 1;
4 is a circuit diagram for explaining the inverter of FIG. 1;
5 is a flowchart illustrating a method of operating a motor driving device according to an embodiment of the present invention.
6 is a graph for explaining a relationship between a reference voltage and a reference time.
7 is a graph for explaining the operation of a motor driving device according to an embodiment of the present invention.

Advantages and features of the present invention, and methods of achieving them, will become clear with reference to the detailed description of the following embodiments taken in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms, and only these embodiments make the disclosure of the present invention complete, and common knowledge in the art to which the present invention belongs. It is provided to completely inform the person who has the scope of the invention, and the present invention is only defined by the scope of the claims. Like reference numbers designate like elements throughout the specification.

Unless otherwise defined, all terms (including technical and scientific terms) used in this specification may be used in a meaning commonly understood by those of ordinary skill in the art to which the present invention belongs. In addition, terms defined in commonly used dictionaries are not interpreted ideally or excessively unless explicitly specifically defined.

Hereinafter, a motor driving device according to an embodiment of the present invention will be described with reference to FIGS. 1 to 7 .

1 is a block diagram showing a motor driving device according to an embodiment of the present invention. FIG. 2 is a circuit diagram illustrating a voltage detection unit of FIG. 1 .

Referring to FIGS. 1 and 2 , a motor driving device according to an embodiment of the present invention may include a motor 110 , an inverter 120 and a control unit 130 .

The motor 110 may include a stator in which a three-phase coil (not shown) is wound, and a rotor disposed in the stator and rotated by a magnetic field generated by the three-phase coil. When three-phase AC voltages Vua, Vvb, and Vwc are supplied from the inverter 120 to the three-phase coil, the motor 110 rotates the permanent magnet included in the rotor according to the magnetic field generated from the three-phase coil.

For reference, the present invention is not limited to a three-phase motor operated by a three-phase coil, and may further include, for example, a single-phase motor using a single-phase coil. Hereinafter, the characteristics of the present invention will be described based on a three-phase motor.

The motor 110 may include an induction motor, a blushless DC motor (BLDC motor), a reluctance motor, and the like. For example, the motor 110 may include a surface-mounted permanent-magnet synchronous motor (SMPMSM), an interior permanent magnet synchronous motor (IPMSM), and a synchronous reluctance motor. (Synchronous Reluctance Motor; Synrm) and the like.

The inverter 120 may include 3-phase switch elements (not shown). The three-phase switch elements are switched on and off when an operation control signal (hereinafter referred to as a 'PWM (Pulse Width Modulation) signal', hereinafter, a PWM signal) supplied to the control unit 130 is input, and the input DC voltage (Vdc) can be converted into 3-phase AC voltage (Vua, Vvb, Vwc) and supplied to the 3-phase coil. A detailed description of the three-phase switch elements will be described below.

When the target command value is input, the control unit 130 determines the on-time interval for the on operation and the off-time interval for the off operation of each of the three-phase switch elements based on the target command value and the electrical angular position of the rotor. A signal (PWMS) can be output.

The motor driving device may further include an input current detector (A), a voltage detector (B), a DC link capacitor (C), a motor current detector (E), an input voltage detector (F), and inductors (L1, L2). can However, the present invention is not limited thereto, and some of the above additional components may be omitted.

The input current detector A can detect the input current ig input from the commercial AC power supply 101 . To this end, as the input current detector A, a current transformer (CT), a shunt resistor, or the like may be used. The detected input current ig is a discrete signal in the form of a pulse and may be input to the control unit 130 for power control.

The input voltage detector F may detect the input voltage vg input from the commercial AC power supply 101 . To this end, the input voltage detector F may include a resistance element, an amplifier, and the like. The detected input voltage vg is a discrete signal in the form of a pulse and may be input to the control unit 130 for power control.

The inductors L1 and L2 are disposed between the commercial AC power supply 101 and the rectifier 105 to perform operations such as noise removal.

The rectifying unit 105 rectifies and outputs the commercial AC power supply 101 that has passed through the inductors L1 and L2. For example, the rectifier 105 may include a full bridge diode to which four diodes are connected, but may be variously modified and applied.

Capacitor C stores the input power. In the drawing, one element is exemplified as the DC link capacitor (C), but a plurality of elements may be provided to secure element stability.

The voltage detection unit (B) of the DC link can detect the DC voltage (Vdc) of both ends of the capacitor (C). That is, the voltage detector (B) can measure the DC voltage (Vdc) applied to the input terminal of the inverter (120). The direct current voltage (Vdc), as a discrete signal in the form of a pulse, is provided to the control unit 130 to generate a PWM signal (PWMS).

To this end, the voltage detector B may include a resistance element, an amplifier, and the like.

Specifically, referring to FIG. 2 , the voltage detector B senses the DC voltage Vdc applied to the inverter 120 using a voltage distribution method based on the reference voltage Vref. At this time, the voltage detector (B) senses the DC voltage (Vdc) by using a plurality of resistance elements (R1, R2, R3), capacitors (C1, C2), diode (D).

First, the first resistance element R1 and the second resistance element R2 are connected in series and connected in parallel to the input terminal of the inverter 120 . At this time, one end of the first resistance element R1 is connected to one end of the inverter 120 and the other end is connected to the second node N2. The second resistance element R1 has one end connected to the second node N2 and the other end connected to the other end of the inverter 120 .

Additionally, the second capacitor C2 has one end connected to the second node N2 and the other end connected to the other end of the inverter 120 . For reference, the second capacitor C2 may be omitted in some other embodiments.

The third resistor element R3 and the first capacitor C1 are connected in series with each other. At this time, the third resistance element R3 has one end connected to the first node N1 and the other end connected to the second node N2. The first capacitor C1 has one end connected to the first node N1 and the other end connected to the other end of the inverter 120 .

The diode D has one end connected to the first node N1 and the other end connected to the reference voltage Vref, and a current flowing from the first node N1 toward the reference voltage Vref.

Here, the control unit 130 senses the voltage applied to the first node N1 and calculates the DC voltage Vdc applied to the input terminal of the inverter 120 based on the sensing voltage.

However, the circuit of the voltage detector B shown in FIG. 2 may be variously modified and implemented, and the present invention is not limited thereto. The control unit 130 may calculate the DC voltage Vdc applied to the input terminal of the inverter 120 based on the data received from the voltage detector B.

Referring back to FIG. 1 , the motor current detector E detects the output current io flowing between the inverter 120 and the three-phase motor 110 . That is, the current flowing through the three-phase motor 110 is detected. The motor current detection unit E may detect all of the output currents ia, ib, and ic of each phase, or may detect the output currents of two phases using a three-phase balance.

The motor current detector E may be located between the inverter 120 and the three-phase motor 110, and a current transformer (CT), a shunt resistor, or the like may be used to detect the current.

Accordingly, the control unit 130 determines the input current (ig) detected by the input current detector (A), the input voltage (vg) detected by the input voltage detector (F), and the DC voltage (detected by the voltage detector (B)). Vdc) and the output current io detected by the motor current detector E may be used to control the operation of the inverter 120 .

The detected output current io may be applied to the control unit 130 as a discrete signal in the form of a pulse, and a PWM signal PWMS is generated based on the detected output current io. Hereinafter, an example in which the detected output current io is a three-phase output current ia, ib, and ic will be described.

Figure 3 is a block diagram showing the components of the control unit of Figure 1;

Referring to FIG. 3, the control unit 130 includes a 3-phase/2-phase axis conversion unit 210, a position estimation unit 220, a speed calculation unit 230, a command value generator 240, a 2-phase/3-phase axis It may include a conversion unit 250 and a signal generator (hereinafter referred to as a 'PWM generator', 260).

The 3-phase/2-phase shaft conversion unit 210 receives the 3-phase currents (ia, ib, ic) output from the motor 110 and converts them into 2-phase currents (iα, iβ) of the stationary coordinate system.

Meanwhile, the three-phase/two-phase axis conversion unit 210 may convert the two-phase currents iα and iβ of the stationary coordinate system into the two-phase currents id and iq of the rotating coordinate system.

The position estimation unit 220 detects at least one of the three-phase currents ia, ib, ic and the three-phase voltages Va, Vb, and Vc to estimate the position H of the rotor included in the motor 110 can do.

)를 연산할 수 있다. 즉, 속도 연산부(230)는 위치(H)를 시간으로 나누어 현재 속도(

)를 연산할 수 있다.The speed calculator 230 is based on at least one of the position H estimated by the position estimation unit 220 and the three-phase voltages Va, Vb, and Vc, and the current speed

) can be computed. That is, the speed calculation unit 230 divides the position (H) by time and the current speed (

) can be computed.

)와 연산된 현재 속도(

)를 출력할 수 있다.In addition, the speed calculator 230 calculates the electrical angle position (based on the position H) (

) and the computed current speed (

) can be output.

The command value generator 240 may include a current command generator 242 and a voltage command generator 244 .

)와 입력된 목표 지령값에 대응하는 지령 속도(ω_r)에 기초하여, 속도 지령치(ω^* _r)를 연산한다.The current command generator 242 calculates the current speed (

) and the command speed ω _r corresponding to the input target command value, the speed command value ω ^* _r is calculated.

Then, the current command generation unit 242 generates a current command value (i ^* _q ) based on the speed command value (ω ^* _r ).

)와 지령 속도(ω_r)의 차이인 속도 지령치(ω^* _r)에 기초하여, PI 제어기(243)에서 PI 제어를 수행하며, 전류 지령치(i^* _q)를 생성할 수 있다. 전류 지령 생성부(242)는 q축 전류 지령치(i^* _q)의 생성시, d축 전류 지령치(i^* _d)를 함께 생성할 수 있다. 한편, d축 전류 지령치(i^* _d)의 값은 0으로 설정될 수도 있다. For example, the current command generation unit 242 is the current speed (

) and the speed command value (ω ^* _r ), which is the difference between the command speed (ω _r ), the PI controller 243 performs PI control and generates a current command value (i ^* _q ). When generating the q-axis current command value (i ^* _q ), the current command generation unit 242 may also generate the d-axis current command value (i ^* _d ). Meanwhile, the value of the d-axis current command value (i ^* _d ) may be set to 0.

In addition, the current command generation unit 242 may further include a limiter (not shown) for limiting the level of the current command value (i ^* _q ) so that it does not exceed an allowable range.

The voltage command generator 244 includes the d-axis and q-axis currents (i _d , i _q ) converted to the rotational coordinate system, and the current command values (i ^* _d , i ^* _q ) in the current command generator 242 and the like. Based on , d-axis and q-axis voltage command values (v ^* _d , v ^* _q ) are generated.

For example, the voltage command generation unit 244 performs PI control in the PI controller 245 based on the difference between the q-axis current (i _q ) and the q-axis current command value (i ^* _q ), and A voltage command value (v ^* _q ) can be generated.

In addition, the voltage command generator 244 performs PI control in the PI controller 246 based on the difference between the d-axis current (i _d ) and the d-axis current command value (i ^* _d ), and the d-axis voltage A command value (v ^* _d ) can be created.

Meanwhile, the value of the d-axis voltage command value (v ^* _d ) may be set to 0 corresponding to the case where the value of the d-axis current command value (i ^* _d ) is set to 0.

Meanwhile, the voltage command generation unit 244 may further include a limiter (not shown) for limiting the level of the d-axis and q-axis voltage command values (v ^* _d and v ^* _q ) so that they do not exceed an allowable range. .

On the other hand, the generated d-axis and q-axis voltage command values (v ^* _d , v ^* _q ) are input to the 2-phase/3-phase axis conversion unit 250.

)와, d축, q축 전압 지령치(v^* _d, v^* _q)를 입력받아, 축변환을 수행한다.The 2-phase/3-phase axis conversion unit 250 is the position calculated by the speed calculation unit 230 (

) and the d-axis and q-axis voltage command values (v ^* _d , v ^* _q ), and performs axis conversion.

)가 사용될 수 있다.First, the 2-phase/3-phase axis conversion unit 250 converts the 2-phase rotating coordinate system into the 2-phase stationary coordinate system. At this time, the electrical angle position calculated by the speed calculator 230 (

) can be used.

Then, the 2-phase/3-phase axis conversion unit 250 performs conversion from the 2-phase stationary coordinate system to the 3-phase stationary coordinate system. Through this conversion, the 2-phase/3-phase shaft conversion unit 250 outputs 3-phase output voltage command values (v ^* a, v ^* b, v ^* c).

The PWM generator 260 generates and outputs a PWM signal (PWMS) for an inverter according to a pulse width modulation (PWM) scheme based on the three-phase output voltage command values (v ^* a, v ^* b, v ^* c).

The PWM signal PWMS may be converted into a gate driving signal by a gate driver (not shown) and input to gates of three-phase switching elements in the inverter 120 . As a result, the three-phase switching elements in the inverter 120 perform a switching operation.

) 및 3상 전압(Va, Vb, Vc)를 기반으로 PWM 신호(PWMS)의 온 시간구간 및 오프 시간구간을 가변시켜, 상기 3상 스위치소자들의 스위치 동작을 제어할 수 있다.Here, the PWM generation unit 260 is the above-described electrical angle position (

) and the three-phase voltages Va, Vb, and Vc, it is possible to control the switching operation of the three-phase switch elements by varying the on-time period and off-time period of the PWM signal PWMS.

The PWM generation unit 260 is set with a plurality of algorithms for generating the PWM signal (PWMS). The PWM generation unit 260 may generate an output voltage command value vector based on the three-phase output voltage command values (v ^* a, v ^* b, v ^* c). For reference, the PWM generation unit 260 may control the output voltage of the inverter 120 using space vector PWM (SVPWN).

In addition, the PWM generator 260 may determine whether to output the PWM signal PWMS based on the DC voltage Vdc input to the inverter 120 sensed through the voltage detector B.

Specifically, the PWM generator 260 determines that the DC voltage Vdc of the inverter 120 is smaller than the reference voltage Vref at which the inverter 120 can normally operate. Measure the detection time (Ts) that is kept smaller than Vref).

Subsequently, the PWM generator 260 sets the PWM signal PWMS provided to the inverter 120 to '0' when the detection time Ts becomes greater than the reference time Tref (ie, the PWM signal PWMS) disable or block).

Here, the reference time Tref may be varied depending on the reference voltage Vref.

A detailed description of the algorithm of the aforementioned PWM generation unit 260 will be described later with reference to FIGS. 5 to 7 .

4 is a circuit diagram for explaining the inverter of FIG. 1;

Referring to FIG. 4 , an inverter 120 according to an embodiment of the present invention may include 3-phase switch elements.

The 3-phase switch element is switched on and off by the PWM signal (PWMS) supplied from the control unit 130 to convert the input DC voltage (Vdc) to the 3-phase AC voltage (Vua, Vvb, Vwc) having a predetermined frequency or duty. ) and output to the motor 110.

In the three-phase switch elements, the first to third upper arm switches Sa, Sb, and Sc and the first to third lower arm switches S'a, S'b, and S'b connected in series with each other form a pair, A total of three pairs of first to third upper arm switches and first to third lower arm switches (Sa&S'a, Sb&S'b, Sc&S'c) may be connected in parallel to each other.

That is, the first phase, the lower arm switch (Sa, S'a) is a three-phase AC voltage (Vua, Vvb, Vwc) to the first phase coil (La) of the three-phase coil (La, Lb, Lc) of the motor 110 ) of which the first phase AC voltage Vua is supplied.

In addition, the second phase, lower arm switch (Sb, S'b) supplies the second phase AC voltage (Vvb) to the second phase coil (Lb), and the third phase, lower arm switch (Sc, S'c) The third-phase AC voltage Vwc may be supplied to the third-phase coil Lc.

Here, each of the first to third upper arm switches Sa, Sb, and Sc and the first to third lower arm switches S'a, S'b, and S'b are turned on and off according to the input PWM signal PWMS. By operating off, the operation of the motor 110 can be controlled by supplying three-phase AC voltages Vua, Vvb, and Vwc to the three-phase coils La, Lb, and Lc, respectively.

5 is a flowchart illustrating a method of operating a motor driving device according to an embodiment of the present invention. 6 is a graph for explaining a relationship between a reference voltage and a reference time. 7 is a graph for explaining the operation of a motor driving device according to an embodiment of the present invention.

Here, FIG. 5 is a flowchart illustrating an abnormal operation prevention algorithm performed by the PWM generation unit 260 of the control unit 130, and FIG. It is a diagram showing the change of the reference time (Tref).

First of all, referring to FIG. 5, the PWM generator 260 of the control unit 130 measures the DC voltage Vdc applied to the input terminal of the inverter 120 based on the data measured by the voltage detector B. (S110).

Here, the voltage detector (B) senses a value proportional to the DC voltage (Vdc) based on the voltage distribution method, and the PWM generator 260 can calculate the DC voltage (Vdc) based on the sensed value. there is.

Next, the PWM generation unit 260 compares the level of the DC voltage Vdc applied to the inverter 120 and the reference voltage Vref (S120).

Here, the reference voltage Vref means a reference value set for the inverter 120 to operate normally. The reference voltage (Vref) may be determined by the specifications of the inverter 120 itself or the motor 110 connected to the inverter 120 and peripheral circuits, and the user can reliably protect the system through an interface (not shown). The reference voltage (Vref) can be set.

In this case, the reference voltage Vref may be preset and stored in a memory (not shown) of the control unit 130, and the value may be changed and applied according to the type and operation mode of the motor 110. The user may select and use the reference voltage Vref previously stored in the memory (not shown) of the control unit 130 .

The PWM generator 260 compares the magnitude of the reference voltage Vref and the DC voltage Vdc set by the user, and when the DC voltage Vdc is greater than the reference voltage Vref, the motor 110 operates normally. Subsequently, the operation of step S110 of measuring the direct current voltage (Vdc) is repeatedly performed.

On the other hand, when the DC voltage (Vdc) becomes smaller than the reference voltage (Vref), the PWM generator 260 measures the sensing time (Ts) during which the DC voltage (Vdc) is kept smaller than the reference voltage (Vref), and detects The magnitudes of the time Ts and the reference time Tref are compared (S130).

Here, the reference time Tref is a value that varies depending on the magnitude of the reference voltage Vref.

Referring to FIG. 6 for convenience of description, in the change of the DC voltage Vdc with time, the first reference time Tref1 for the first reference voltage Vref1 of the first sensing level corresponds to the second sensing level. may be greater than the second reference time Tref2 for the second reference voltage Vref1. That is, when the first reference voltage Vref1 is greater than the second reference voltage Vref1, the first reference time Tref1 is greater than the second reference time Tref2.

In this case, the reference time Tref may decrease as the reference voltage Vref decreases, and the reference time Tref may increase as the reference voltage Vref increases.

The relationship between the reference voltage (Vref) and the reference time (Tref) is that the higher the sensing level in the full-wave rectified DC voltage (Vdc), the larger the reference time (Tref) required for sensing, and the lower the sensing level, the smaller the reference time. it happens because Therefore, when a detection level suitable for an actual system is selected, the reference time Tref should be greater than the detection time Tp, which is the minimum unit for detection, in order to detect an abnormality in the system.

In summary, the reference time (Tref) is determined dependently on the reference voltage (Vref), and when the reference voltage (Vref) is set in advance, the reference time (Tref) is determined according to the set reference voltage (Vref) to generate the PWM unit. (260) is used.

Referring to step S130 of FIG. 5 again, when the detection time Ts is smaller than the reference time Tref, the PWM generator 260 increases the detection time Ts (S140).

This means that the state of the DC voltage (Vdc) needs to be further examined because the reference time (Tref), which is the minimum unit for detecting a voltage anomaly, has not yet elapsed.

Accordingly, the PWM generating unit 260 repeatedly performs steps S110 to S130 to determine whether the DC voltage Vdc is continuously kept smaller than the reference voltage Vref.

Subsequently, when the detection time Ts becomes greater than the reference time Tref, the PWM generator 260 turns off the control command output to the inverter 120 (S150). That is, the PWM generation unit 260 blocks the PWM signal PWMS output to the inverter 120 or deactivates all signals of the PWM signal PWMS (eg, sets a logic value '0').

Additionally, when measuring the detection time Ts, the PWM generation unit 260 may continuously measure and use the time during which the DC voltage Vdc becomes lower than the reference voltage Vref. This is referred to as the continuation detection time Tcp, and the PWM generator 260 may determine whether to turn off the control command by comparing the continuation detection time Tcp with the reference time Tref.

In addition, although not clearly specified in the drawings, when the DC voltage (Vdc) becomes greater than the reference voltage (Vref) after the control unit 130 cuts off the PWM signal (PWMS) provided to the inverter 120, PWM is generated. The unit 260 may again provide the PWM signal PWMS to the inverter 120 as originally.

Through this, the inverter 120 can operate normally again, and the motor driving device can also be normally restarted.

In summary, when power is normally applied to the control unit 130 and abnormal power is temporarily applied to the inverter 120, the control unit 130 temporarily sends a PWM signal (PWMS) to prevent abnormal operation of the inverter 120. ) is blocked. Subsequently, when normal power is applied to the inverter 120, the control unit 130 may control the motor 110 to be normally driven by providing a PWM signal (PWMS) to the inverter 120 again.

For example, when the reference voltage (Vref) is 100V and the reference time (Tref) is 12.5 ms, the control unit 130 determines whether the DC voltage (Vdc) input to the inverter 120 is lower than 100V. and if the detection time (Tp) when the DC voltage (Vdc) is lower than 100V is longer than 12.5 ms, the PWM signal (PWMS) is cut off.

FIG. 7 is a diagram for explaining a comparison between a waveform before an abnormal operation prevention algorithm is applied in the PWM generator 260 and a waveform after the application.

Referring to FIG. 7 , when the control unit 130 does not perform the above-described abnormal operation prevention algorithm, abnormal power is applied to the inverter 120 at the first time T1 and the second time Tp has elapsed. At time T2, a peak current may occur in the inverter 120 or the motor 110 (S1 in FIG. 7).

This is a phenomenon that occurs when the internal command value of the control unit 130 continues to increase as the discrepancy between the target value of the control unit 130 and the current value of the motor 110 continues.

When a peak current is generated in the motor 110 or the inverter 120, burnout may occur in parts included in the motor driving device, and the temperature of the motor 110 rises abnormally, causing the coil or The rotor may ignite or the bearings may be damaged.

On the other hand, when the control unit 130 performs the above-described abnormal operation prevention algorithm, when abnormal power is applied to the inverter 120 at the first time T1, the control unit 130 controls the PWM applied to the inverter 120. Blocks or disables the signal (PWMS).

Through this, the control unit 130 prevents peak current from occurring in the motor 110 or the inverter 120 due to abnormal power applied to the inverter 120, thereby deteriorating and igniting the motor driving device. can be prevented (S2 in FIG. 7).

In summary, the motor driving device according to an embodiment of the present invention detects whether or not abnormal power is applied to the inverter 120 and stops the motor 110 based on this, thereby preventing abnormal peak current from occurring. and ensure the stability of motor control. In addition, the generation of abnormal peak current can be prevented only by changing the algorithm of the control unit 130 without adding a separate abnormal current detection device, thereby reducing the unit cost of motor production and maximizing company profits.

In addition, in the motor driving device according to an embodiment of the present invention, in an abnormal situation in which the input power applied to the inverter 120 is cut off, the motor 110 and other parts may be damaged due to an abnormal peak current, or a fire may occur due to this. can prevent this from happening.

In addition, the motor driving device according to an embodiment of the present invention, when the input power applied to the inverter 120 returns to normal, by reliably restarting the motor, automatically after the occurrence of temporary input power abnormality is resolved. You can make your system recover. Through this, the convenience of the manager and the stability of the system can be improved.

The above-described present invention, since various substitutions, modifications, and changes are possible to those skilled in the art without departing from the technical spirit of the present invention, the above-described embodiments and accompanying drawings is not limited by

101: commercial AC power supply 105: rectifier
110: motor 120: inverter
130: control unit

Claims (10)

an inverter that converts the DC voltage received into AC voltage and provides it to the motor;
a voltage detector sensing the level of the DC voltage applied to the inverter; and
Including a control unit for outputting a PWM signal for controlling the operation of the switching element included in the inverter,
The control unit,
When the DC voltage sensed by the voltage detector is smaller than the reference voltage, measuring a sensing time during which the DC voltage is maintained smaller than the reference voltage;
When the detection time is greater than the reference time, cut off the PWM signal provided to the inverter;
The control unit,
When the detection time is less than the reference time, increasing the detection time while the DC voltage is maintained less than the reference voltage
motor drive unit.
delete According to claim 1,
The control unit,
Measuring a continuous sensing time during which the DC voltage continues to be less than the reference voltage;
When the continuous detection time is greater than the reference time, blocking the PWM signal provided to the inverter
motor drive unit.
an inverter that converts the DC voltage received into AC voltage and provides it to the motor;
a voltage detector sensing the level of the DC voltage applied to the inverter; and
Including a control unit for outputting a PWM signal for controlling the operation of the switching element included in the inverter,
The control unit,
When the DC voltage sensed by the voltage detector is smaller than the reference voltage, measuring a sensing time during which the DC voltage is maintained smaller than the reference voltage;
When the detection time is greater than the reference time, cut off the PWM signal provided to the inverter;
The reference time is calculated based on the magnitude of the reference voltage,
When the size of the reference voltage is reduced, the size of the reference time is reduced
motor drive unit.
According to claim 4,
The reference voltage is preset and stored in the memory of the control unit, and the value is changed according to the operation mode of the motor.
motor drive unit.
According to claim 1,
The control unit,
Providing the PWM signal to the inverter again when the DC voltage sensed by the voltage detector is greater than the reference voltage
motor drive unit.
A motor including a stator around which a three-phase coil is wound and a rotor disposed within the stator and rotated by a magnetic field generated from the three-phase coil;
an inverter including three-phase switch elements that operate on and off to supply and cut off the three-phase AC voltage to the three-phase coil;
a voltage detector for sensing the magnitude of the DC voltage applied to the inverter; and
Including a control unit for outputting a PWM signal for controlling the operation of the three-phase switch elements,
The control unit,
When the DC voltage sensed by the voltage detector is smaller than the reference voltage, measuring a sensing time during which the DC voltage is maintained smaller than the reference voltage;
When the detection time is greater than the reference time, cut off the PWM signal provided to the inverter;
The control unit,
When the detection time is less than the reference time, increasing the detection time while the DC voltage is maintained less than the reference voltage
motor drive unit.
delete According to claim 7,
The control unit,
Providing the PWM signal to the inverter again when the DC voltage sensed by the voltage detector is greater than the reference voltage
motor drive unit.
A motor including a stator around which a three-phase coil is wound and a rotor disposed within the stator and rotated by a magnetic field generated from the three-phase coil;
an inverter including three-phase switch elements that operate on and off to supply and cut off the three-phase AC voltage to the three-phase coil;
a voltage detector for sensing the magnitude of the DC voltage applied to the inverter; and
Including a control unit for outputting a PWM signal for controlling the operation of the three-phase switch elements,
The control unit,
When the DC voltage sensed by the voltage detector is smaller than the reference voltage, measuring a sensing time during which the DC voltage is maintained smaller than the reference voltage;
When the detection time is greater than the reference time, cut off the PWM signal provided to the inverter;
The three-phase coil,
A first-phase coil to which the first-phase AC voltage of the three-phase AC voltage is supplied, a second-phase coil to which the second-phase AC voltage of the three-phase AC voltage is supplied, and a third-phase AC of the three-phase AC voltage A third phase coil to which voltage is supplied,
The three-phase switch elements,
A first upper arm switch and a first lower arm switch connected in parallel with the first phase coil and operating on and off to supply the first phase AC voltage;
A second upper arm switch and a second lower arm switch connected in parallel with the second phase coil and operating on and off to supply the second phase AC voltage;
A third upper arm switch and a third lower arm switch connected in parallel with the third phase coil for on and off operation so that the third phase AC voltage is supplied,
The control unit turns off all of the three-phase switch elements when the detection time is greater than the reference time.
motor drive unit.

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