WO2014003223A1

WO2014003223A1 - Pwm control apparatus for sequential motor start-up

Info

Publication number: WO2014003223A1
Application number: PCT/KR2012/005184
Authority: WO
Inventors: 최윤식; 명기성; 서성규; 김상곤
Original assignee: 휴먼전자 주식회사
Priority date: 2012-06-27
Filing date: 2012-06-29
Publication date: 2014-01-03

Abstract

The present invention relates to a PWM control apparatus for the sequential start-up of a motor, in which a motor is started and driven while limiting the starting current, and in which abnormal operations of a device are detected and the device is protected. The apparatus has the effect of greatly reducing the instantaneous voltage drop and the starting current and of stabilizing power quality in a distribution system through the adoption of a PWM sequential start-up control scheme which prevents a plurality of inductive loads from being instantly and simultaneously started.

Description

Sequential start PWM control device of motor

The present invention relates to a sequential start PWM control apparatus for a motor for detecting and protecting abnormal operation of a device while starting and limiting a starting current during starting and driving of an electric motor used in an air conditioner or a refrigerator.

Recently, there has been a frequent occurrence of disruption in power supply due to the surge in the use of inductive loads such as air conditioners and refrigerators.

In general, when an inductive load is connected to an AC power source, surge current or inrush current is generated. Under normal operating conditions of inductive loads, the phase difference between the voltage and current of the power source connected to the inductive load is 90 °. This is because the instantaneous flux change rate of the inductive load occurs at the same time as the instantaneous voltage drop. Collectively referred to as starting current). However, if a sudden voltage change occurs when a power source is not connected to an inductive load, the voltage and current phases coincide, and the rate of change of the magnetic flux in the load increases momentarily, which leads to a sudden rise in starting current.

This inductive load consumes 5-10 times higher starting current than the rated current during start-up, which induces instantaneous voltage drop in the power system using the same switchboard, resulting in malfunction or failure of various electrical and electronic devices. May result. In addition, the high starting current of the inductive load may result in the destruction of the motor itself and the decrease of the reserve ratio of the transformer in the switchboard, or in severe cases, may cause the transformer to fail.

In order to minimize the effect of these inductive loads on the power system, the International Electrotechnical Commissi-on established the IEC 61000-3-3 standard as part of the electromagnetic compatibility standard in 1994, Limits of voltage transients have begun for electrical and electronic products with rated current.

The IEC 61000-3-3 international standard has been applied only to European countries, mainly in 230 V, 50 Hz electrical environments (EN 61000-3-3), but the adverse effects of momentary voltage fluctuations on the power system due to the activation of inductive loads are gradually increasing. Due to the growing global trend, recently, China (GB 17625-2), Japan (C61000-3-3), Australia / New Zealand (AS / NZS 61000-3-3), Korea (K 61000-3-3) It is adopted as a new electrical safety standard in many countries of the world. In Australia and New Zealand, in addition to limiting the voltage fluctuation allowance, the current value limit is also simultaneously implemented such as limiting the starting current of the inductive load to 45A or less in each region.

Such transient voltage fluctuation or limit of starting current is mainly required in loads using single-phase induction motors such as air conditioners, refrigerators, and vacuum cleaners. As a way to solve this problem, resistive loads (resistance or thermistors) on the starting coils are solved. Is added only at the start of the load to reduce the starting current and voltage drop.

Although the instantaneous voltage drop of the inductive load can be alleviated to some extent by the insertion of a low-cost resistive load, the relaxation rate is not high as the load capacity increases, and the ambient temperature is accompanied by high heat generation due to the characteristic of the resistive load. Continuous operation of inductive loads in high-temperature environments was not an ideal solution because its performance drastically degraded or even resistive loads were destroyed.

The present invention was devised to improve the above problems, and provides a sequential starting PWM control apparatus for an electric motor for instantaneous voltage drop and starting current attenuation, which can prevent the instantaneous voltage drop and the inrush current from flowing when the inductive load is started. Its purpose is to.

A sequential starting PWM control device of an electric motor for instantaneous voltage drop and starting current attenuation caused by inductive load starting according to the present invention is a control device for controlling an electric motor, comprising: a power supply unit supplying electric power to the electric motor, the power supply unit A current limiter which is connected in series with the main coil of the motor operated by the switch to perform the current attenuation function by switching on / off, and controls the current limiter to be switched on / off to start a plurality of inductive loads A plurality of subordinate control unit for limiting the incoming inrush current generated by the; And a main controller to control each of the plurality of subordinate control units to sequentially start the plurality of inductive loads in a time division multiple manner such that the plurality of inductive loads are not simultaneously started.

The main controller may control the plurality of slave controllers using power line communication.

The main controller may be configured to sequentially start the plurality of subordinate control units in a time division multiple access manner so that the plurality of subordinate control units are not simultaneously activated by receiving a start signal from the subordinate control unit.

The method may further include: setting a number of slave controllers, generating a synchronization indicator signal in which the slave controllers start sequentially, and receiving a start request from the slave controller according to the synchronization indicator signal; Including the step of sending a start response signal to start the slave control unit, characterized in that for starting the plurality of slave control units sequentially in a time division multiple access method.

In addition, the plurality of subordinate control units, respectively receiving a synchronization indicator signal from the main control unit, transmitting a start request signal to the main control unit after the time set by the synchronization indicator signal, receiving the start response signal from the main control unit And controlling the inductive load to start up during the start time set by the synchronization indicator signal.

According to the present invention configured as described above, soft switching by using a PWM control method using TRIAC in order to minimize the voltage drop and the sudden rise of the starting current caused by the increase in the use of the inductive load forming the network in the switchboard This has a possible effect.

In addition, by applying a sequential start control method that prevents a large number of inductive loads from starting simultaneously at the same time, it greatly reduces the instantaneous voltage drop and starting current, thereby reducing the power cost imposed on the maximum power consumption or inductive There is an effect that can stabilize the power quality of the same distribution system connected to the load network.

Figure 1a is a view showing a sequential start PWM control apparatus of the motor according to the present invention, Figure 1b is an enlarged view of portion A of Figure 1a.

FIG. 2 is a graph showing the voltage variation of the main coil when the above-mentioned PWM control is not used when the air conditioner compressor is started. FIG. 3 is a graph illustrating the voltage variation of the main coil when the PWM control is used.

Figure 4 is a flow chart illustrating a control process of the sequential start PWM control apparatus of the motor according to the present invention.

5 is a diagram illustrating a control relationship between a main controller and a slave controller of a sequential start PWM control apparatus of an electric motor according to the present invention.

FIG. 6 is a diagram illustrating the detailed protocol of FIG. 5.

7A is a diagram illustrating the starting current characteristics of the air conditioner compressor when the TRIAC PWM module is not applied, and FIG. 7B is a diagram illustrating the starting current characteristics of the air conditioner compressor when the TRIAC PWM module is applied.

8 is a flowchart illustrating an operation sequence of the main control unit in the case where the slave control unit of N exists.

9 is a diagram illustrating an operation flowchart of the slave controller.

Hereinafter, a sequential start PWM control apparatus of an electric motor according to an exemplary embodiment of the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 1A, the control device 100 according to the present invention includes a power supply unit 110, an electric motor 120, a current limiting unit 131, a first relay RY1 141, and a second relay RY2 ( 142, the third relay (RY3) 143, the first signal detector 150, the second signal detector 160, the supporter 170, the main controller 181, the slave controller 183, and the display unit ( 185).

The power supply unit 110 supplies AC power.

One end of the electric motor 120 is connected to be supplied with power to the power supply unit 110 through the first relay 141, and is branched into the main coil 121 and the auxiliary coil 122. In the present invention, for convenience of description, the electric motor 120 will be described as driving a compressor.

The current limiting unit 131 is connected in series with the main coil 121 of the motor 120 and is controlled by the subordinate control unit 183 at the start so that the power attenuating function to the main coil 121 can be performed. In the present invention, a triac (TRIAC) is described as a reference, and the triac is driven by pulse width modulation (PWM) control to reduce an instantaneous voltage drop or starting current of an inductive load. .

This is a soft switching method that enables the proper distribution of power supply when starting an inductive load by using an electronic switching element that is much faster than the frequency of the load. The likelihood of malfunctions is reduced. In addition, it is possible to effectively attenuate the instantaneous voltage drop and the starting current by synchronizing the phases of voltage and current.

As shown in FIG. 2, in the case of the inductive load not controlling the phase, the inductive load starts at the upper end of the supplied AC voltage, thereby causing a relatively large instantaneous voltage drop.

On the other hand, when the PWM method is applied as shown in FIG. 3, the phase of the supply voltage for power delivery can be controlled to start from zero, and the voltage supply of the initial starting current generation section can be gradually increased, thereby providing an instantaneous voltage. Soft start with strong but minimal generation of starting current is possible.

Figure 3 shows the voltage fluctuations of the main coil when starting the air conditioner compressor (rated drive power of the WHS-302BD model of Mandowinia Co., Ltd.) of rated power consumption 3kW applied TRIAC PWM module according to the present invention. The measured results show that the voltage phase for starting the inductive load is not only zero-crossed, but the voltage supply of the starting current generation section is properly controlled by the PWM method.

The first relay 141 is installed on the power supply path between the power supply unit 110 and the motor 120 so as to be controlled by the subordinate control unit 183 to control the supply of power to the motor 120.

The second relay 142 is connected in parallel with the current limiting unit 131 so that the current control path of the main coil 121 can be controlled and handled by the slave control unit 183 when the motor 120 is started. .

The support unit 170 is connected to the auxiliary coil 123 of the motor 120 to support starting compensation and driving. The support unit 170 is connected to the auxiliary coil 123 of the motor 120 to be driven as a driving support unit to support driving. The driving condenser 171 is connected to the auxiliary coil 123 of the motor 120 in parallel with the condenser 171 and the driving capacitor 171 as a starting compensation support unit for compensating starting torque of the motor 120 at startup. And a third relay 143 connected in series with the start compensating capacitor 173 and the start compensating capacitor 173 connected in parallel with each other.

The first signal detector 150 is connected to the input / output terminal of the current limiting unit 131 to detect the voltage change signal of the main coil 121 of the motor 120 and provide it to the slave controller 183.

The first signal detector 150 is connected to the input / output terminal of the current limiter 121, that is, connected in parallel with the current limiter 131 to rectify the voltage change signal of the main coil 121 of the motor 120. A rectifier element 151 for outputting and a first port coupler 153 for outputting a voltage output from the rectifier element 151 to the slave controller 183 are applied.

As the rectifier 151, a bridge diode is applied.

The second signal detector 160 is connected in parallel with the starting compensation capacitor 173 to provide the slave controller 183 with a voltage change signal of the auxiliary coil 123 of the motor 120.

A second port coupler 163 is also applied to the second signal detector 150.

The main controller 181 controls the slave control unit 183 to reduce the instantaneous voltage drop and the starting current rise width by a plurality of inductive loads, which will be described in detail later.

The display unit 185 is controlled by the slave controller 183 to display driving state information of the electric motor 120.

The slave control unit 183 performs a control function for the start of the motor 120 and the driving after the start, and the motor 120 from each voltage change signal provided from the first and second signal detection units 150 and 160. Determine the operation and abnormality, and receive the operation signal for the motor 120 to apply a pulse signal with the duty set for the current limiter 131 at the time of starting the motor 120 current limiter 131 Limits the inrush current by controlling the switching to on / off duty for on-drive ratio for the set period.

Here, as the set duty value increases, the current flowing through the current limiting unit 131 increases. On the contrary, as the duty value decreases, the current decreases.

Preferably, the duty value may be appropriately set in such a way that the current can be minimized without disturbing the starting of the motor 120.

Here, the drive duty set by the slave control unit 183 may be set within a range capable of increasing the starting efficiency while limiting the inrush current by the current limiting unit 131, preferably set within a duty range of 30 to 50%. do.

Meanwhile, the slave controller 183 first turns on the third relay 143 when the electric motor 120 is driven, and then turns on the first relay 141 after a predetermined time is delayed. In this case, since the discharge phenomenon of the driving capacitor 171 is eliminated and the overcurrent charged in the starting capacitor 171 during the operation of the first relay 141 is largely canceled by the auxiliary coil 123 of the electric motor 120, By eliminating the use of conventional NTC resistors or fixed devices, cost increases are suppressed and structurally simple.

In addition, the size of the current and voltage of the main coil 121 and the auxiliary coil 123 varies depending on whether the rotor of the motor 120 is driven when the motor 120 is started and driven. At the same time, voltages at both ends of the current limiting unit 131 connected in series with the main coil 121 and voltages at both ends of the starting capacitor 173 connected in series with the auxiliary coil 123 are also varied. The units 140 and 150 are responsible for detecting the changed signal and providing the changed signal to the slave controller 183.

The voltage change signal generated by the main coil 121 of the motor 120 is rectified by the rectifying element 151 connected to both ends of the current limiting unit 131, and then the subordinate control unit 183 through the first port coupler 153. Is provided.

The voltage change signal generated by the auxiliary coil 123 of the motor 120 is detected by the second signal detector 160 and provided to the slave controller 183.

The slave controller 183 compares the signals received through the first and second signal detectors 150 and 160 to determine whether the electric motor 120 is rotated, and if the rotation is detected as a result of the determination, the third By turning off the relay 143, the starting capacitor 173 is separated from the driving circuit.

In addition, the slave control unit 183 compares and determines the signals provided from the first and second signal detection units 150 and 160 to determine whether the motor 120 is operating.

In determining the operation of the motor 120, the main coil 121 and the main coil 121 of the electric motor 120 using the first and second port coupler (153, 163) electrically isolated from each other By providing the slave control unit 183 with the voltage change signal generated at the auxiliary coil 123 side, the stability of the circuit is secured. In addition, the rectifying element 151 is used to rectify the voltage change signal generated on the main coil 121 side for each half cycle of the commercial frequency and provide the slave control unit 183 with accurate control in a short time. It is possible to achieve cost reduction and miniaturization of equipment by quickly blocking the voltage rise of the capacitor 173 to prevent component damage due to the instantaneous voltage rise and enabling the use of the starting capacitor 173 having a low withstand voltage.

Each signal from the first and second signal detectors 150 and 160 is used by the slave controller 183 to detect a failure of the overall circuit during the start and drive sections of the device.

That is, the signals from the first and second signal detectors 150 and 160 are all low during the first period until power is supplied to the slave controller 183 and the operation signal is input to the motor 120. If the output is normal, if the operating signal is input to the motor 120 and the low signal is output during the second interval until the third relay 143 is switched on, the output is normal, the third relay 143 After the first relay 141 is switched on and the high signal is all output during the third period after the operation is switched on, the third relay after the first relay 109 is operated to be switched on When the first signal detector 150 is high and the second signal detector 160 is low during the fourth period until the 135 is turned off, the third signal 135 is turned off. During the fifth period until the first relay 141 is turned off, the first signal detection unit 150 senses a high second signal. Unit 160 determines as normal if a low signal is output.

The slave control unit 183 determines that a failure occurs when a signal other than the normal signal for each section described above occurs and turns off the first and third relays 141 and 143 to cut off the power input to the motor 120. The additional failure of the device due to prevent in advance, and displays the failure information through the display unit 185.

On the other hand, the slave control unit 183 controls the power to the motor 120 is cut off when the failure is detected, when the motor 120 is stopped, the display unit 185 continues to display the failure state until the pressure balance of the refrigerant is maintained When the balance of pressure is set after a set time, for example, the motor 120 is attempted to start again.

Next, a control process of the above-described control apparatus will be described with reference to FIG. 4.

First, when power is input through the power supply unit 110 (step S111), when power is applied to the slave controller 181, the device is initialized immediately (step S113), and the slave controller 181 detects a power supply voltage. The display unit 185 indicates that the normal voltage is input, and checks whether an operation signal for driving the motor 120 is input from the main controller (not shown) (step S115).

In addition, the slave controller 181 determines whether the power supply voltage is normally input (step S117), and when it is determined that the voltage of the operable voltage region is not input, the power supply voltage can be operated without starting the motor 120. Wait until you are in the voltage range. Herein, the operating voltage range is 187 to 276V at 50 Hz power, and 187 to 254 V at 60 Hz power.

If it is determined in step S117 that the power supply voltage is normal, the slave control unit 181 compares the signals from the first and second detection signal units 150 and 160 with each other as described above, so that the first relay 141 or It is determined whether the abnormal voltage has flowed into the circuit due to the failure of the second relay 142 (step S119). If it is determined in step S119 that an abnormal voltage has flowed into the circuit, the abnormal state information is displayed on the display unit 185. In contrast, if it is determined that the operation is normal in step S119, the third relay RY3 143 for connecting the starting capacitor 173 is operated to be switched on before the first relay 141, and then after several hundred ms, The relay RY1 141 is switched on (step S121). In this case, the charging current of the driving capacitor 171 does not occur until the first relay 141 operates so that the third relay 143 is not fused by the discharge current from the driving capacitor 171.

Thereafter, when the first relay 141 is operated, that is, turned on, the current limiting unit 131 is switched on / off with a set duty to control the conduction current of the electric motor 120 to the main coil 121. In this way, the starting current is controlled (step S123).

Next, the slave control unit 181 compares the signals output from the first and second detection signal units 150 and 160 with each other to determine whether the electric motor 120 is normally operated and detects whether or not a failure occurs (step S125). ). As a result of the determination, if a failure is detected, the first relay 141 is turned off to stop the motor 120, and the failure state is displayed on the display unit 185 (step S127), and a time example designated as the maximum starting time of the motor 120 is shown. For example, after 3 minutes have elapsed, the operation is returned to step S119. Here, when the driving time of the electric motor 120 is determined before the time designated as the maximum driving time from the operation time of the first relay 141, it is determined as normal system operation.

If it is determined in step S125 that is normal, in order to disconnect the starting capacitor 173 from the circuit and to energize the current on the main coil 121 side of the motor 120 to the second relay 142, the slave control unit 181 is a third control unit. The relay 143 is turned off, the second relay 142 is turned on, and the current limiting part 131 is turned off (step S129).

Subsequently, the slave controller 181 compares the signals input from the first and second signal detectors 150 and 160 to each other to compare the signals of the second and third relays 142 and 143 and the current limiter 131. After checking whether there is a failure and determining whether normal operation proceeds (step S131), if the result of the determination is a failure, the process after step 219 is performed through step S127, and when it is determined that it is operating normally, the motor 120 is continuously Detecting whether the stop signal is received from the main controller (step S133), and when the stop signal is detected, stopping the motor 120 (step S135), and detecting the inflow of the operation signal of the motor 120 (step S115). Return to.

Next, the control operation of the main controller 181 and the slave control unit 183 will be described.

In special situations, such as during periods when power usage by inductive loads is concentrated, or in the case of temporary recovery of power after a power outage, even with inductive loads controlled by the PWM method, at the same time, a high voltage drop and start-up are instantaneously at the switchboard. An increase in current rise is caused.

In order to solve such a problem, it is necessary to control the start of the inductive load device belonging to a given environment to be sequentially started in a time division manner using a communication network, so that a plurality of inductive loads are not started at a specific moment.

In order to control a plurality of inductive loads to be sequentially started, as shown in FIG. 1B, a plurality of subordinate control units 183 inside a management area use communication with each other around the main control unit 181 in a central control manner. Is activated. This prevents a plurality of inductive loads from starting, thereby more efficiently improving the power quality and reducing the maximum power requirement, thereby ensuring energy saving and safety of the power grid.

In order for the main controller 181 to sequentially control the inductive load driven by the plurality of slave controllers 183-1, 183-2, ..., 183-N using a communication network, a wired / wireless LAN Various types of communication methods, such as various types of serial communication, may be used. Among these, the power line communication method is preferable in consideration of the communication distance, the communication application cost, the presence or absence of communication equipment and line facilities, and the configuration environment of the inductive load machine.

As shown in FIG. 1B based on power line communication, the slave controller 183 has a network configuration in the form of a bus around the main controller 181. The sequential control network is composed of one main controller 181 (Master), which will act as an internal controller, and a plurality of subordinate controllers 183-1, 183-2, ..., 183-N for controlling the starting of a plurality of inductive loads. It consists of Slaves.

The sequential start algorithm uses time division multiple access (TDMA) method in the media access control (MAC) method in the communication field, when request loads are concentrated on power line communication. Collision to solve the problem that all the slave control unit 183 is not activated.

The sequential startup basically sends a request message that the slave controller 183 which controls the inductive load that is desired to be started is started by the main controller 181, and sends a corresponding reply message to the main controller 181. It is designed to start only when received from Detailed control methods will be described later.

The sequential start algorithm using the media access control method is a time division multiple access method as shown in FIG. 5, so that a collision does not occur using a device-specific identification number assigned to each slave control unit 183.

The sequential start method is a time division multiple access method as described above. The slave control unit 183 makes a start request at a time zone assigned to the slave controller 181 based on the synchronization indicator signal generated by the main control unit 181, and responds accordingly. Start sequentially by receiving a signal.

The main control unit 181 transmits the synchronization indicator signals to all the slave control units 183-1, 183-2,... At a period determined according to the number N of the plurality of slave control units 183-1, 183-2, ..., 183-N. , 183-N), so that the slave control units 183-1, 183-2, ..., 183-N operate in synchronization.

The slave control unit 183-1, 183-2, ..., 183-N is prioritized by the identifier number set therein, and the starting request is made only in the time zone of the sequence corresponding to its identifier number as shown in FIG. can do. The detailed protocol configuration regarding time setting is shown in FIG. As shown in FIG. 6, when the slave control unit 183 starts up, the slave control unit 183 must start up through the above-described time division sequential start control protocol.

The following describes a process and results of implementing, verifying and analyzing the instantaneous voltage drop and the starting current attenuation method by the sequential starting PWM control device of the motor according to the present invention and the sequential starting control method for preventing simultaneous starting.

FIG. 7A shows the starting current characteristics of the air conditioner compressor when the TRIAC PWM module is not applied. The peak value larger than the effective load starting current of 88.99 Arms shown in the general load shown in Table 1 does not satisfy the international standard. However, when the TRIAC PWM module is applied as in the present invention, it can be seen that the effective starting current (37.46 Arms) and the peak value are attenuated and smoothly started, as shown in FIG. 7B and (Table 1). It is preferable to use TRIAC (Model BTA41) of STMicroelectronics having a rated current of 41 Arms as the power semiconductor device for waveform division control.

Table 1

Test item		Normalload	TRIAC PWM	Limit
Inrush current		88.99 A _rms	37.46 A _rms	45.0 A _rms
Flicker	P _st	2.391	0.667	1.0
	D _c	3.085%	2.214%	3.3%
	D _max	14.698%	4.017%	6.0%
	D (t)	190 ms	130 ms	500 ms

In addition, according to the test results shown in (Table 1), the flicker test item associated with the flicker voltage drop, Pst (short term flicker value) Dc, (relative steady-state voltage change), Dmax (maximum relative voltage change) and D (t) (instant voltage change for more than 500 ms) provide sufficient reserve ratio for all items and satisfy international standard. You can check it. Voltech's PM3000A general purpose power analyzer and IEC Standard 555 reference impedance network were used to test the flicker, the international standard (IEC 61000-3-3). To measure this, Yokogawa's DL1740 digital oscilloscope connected to Tektronix's A621 AC current probe was used.

In summary, according to the sequential starting PWM control apparatus of the motor according to the present invention, it is possible to effectively attenuate the instantaneous voltage drop and the starting current generated when the inductive load is started below the international standard. Verified by international standard measurement result.

Next, the sequential start control in the sequential start PWM control apparatus of the motor according to the present invention will be described.

In the sequential start PWM control apparatus of the motor according to the present invention, the main controller 181 uses power line communication to control the slave loads controlled by the slave control unit 183, and the power line communication has an Infrasys company having a communication speed of 9,600 bps. It is preferable to select the APLC-485MA power line communication module. The reason for choosing such an environment is that the sequential start control method can be applied even in a low speed communication environment.

The sequential control method was implemented using a microcontroller with an 8-bit processor according to the actual product environment. The resources and communication environment are as follows.

20MHz System Clock

1024 bytes SRAM

256 bytes Data EEPROM

-14Kbytes Program Memory

-4 8-bit Timers & 1 16-bit Timer

-1 UART

-16 GPIOs

-Bus type 9600bps power line communication

In order to apply the sequential start control method in the sequential start PWM control apparatus of the motor according to the present invention, the main control unit 181 and the subordinate control unit 183 are implemented and implemented, and the subordinate control unit 183 sets each unique identification number. It was designed to be.

FIG. 8 is a diagram illustrating an operation flowchart of the main controller 181 for the case where the slave control unit 183 of N exists. The main controller 181 synchronizes all slave controllers 183 in the network, responds to a start request, and transmits a synchronization indicator signal at a predetermined time.

The main control unit 181 first sets the number of subordinate control units 183 to be controlled, generates and transmits a synchronization indicator signal for sequential start control (S211, S213). Upon receiving the synchronization indicator signal, the slave control unit 183 may operate the start request only in a time zone allocated by its unique identification number. When the main controller 181 receives the start request signal from the slave controller 183, the main controller 181 transmits a response signal corresponding thereto (S215). After a time period equal to the number of slave controllers 183 in the network, the main controller 181 generates and transmits a synchronization indicator signal again (S231).

9 is a flowchart illustrating an operation of the slave controller 183. The slave control unit 183 recognizes and stores the unique identification number set in the initialization process after powering on and initializes other necessary variables (S311). The operation of the slave controller 183 starts in accordance with the synchronization indicator signal from the main controller 181 (S313).

After receiving the synchronization indicator signal (S321), the user waits until the time zone assigned by the identification number (S323). When the start signal input is activated in the time zone, the main control unit 181 receives the start request signal. Transfer to (S325). When a corresponding response signal is received from the main controller 181 within a predetermined time (in the case of the present invention, set to 10ms), a start signal is output and start operation is performed (S331 and S333). Otherwise, the above operation is repeatedly performed in the next synchronization indicator signal section (S335).

According to the sequential starting PWM control apparatus of the motor according to the present invention, the inductive load is prevented from being instantaneously started by using the medium access control method. According to the results of the implementation and verification according to the actual operating environment, the slave controller 183 normally started all of its own start times by assigning a unique identification number to all slave controllers 183 in the sequential start-up system. Was confirmed not to occur.

Claims

In the control device for controlling the electric motor in the thermal freezer,

A power supply unit supplying power to the electric motor;

A current limiting unit connected to the main coil of the motor operated by the power supply unit in series to perform attenuation function of the current by switching on / off;

A plurality of subordinate control units controlling the current limiting unit to be switched on / off to limit the inrush current which is generated due to a plurality of inductive loads; And

A main control unit controlling each of the plurality of subordinate control units to sequentially start the plurality of inductive loads in a time division multiple manner such that the plurality of inductive loads are not simultaneously started;

Sequentially starting PWM control device of the motor, characterized in that consisting of.
The method of claim 1,

The main fisherman,

And a plurality of subordinate control units using power line communication.
The method according to claim 1 or 2,

The main fisherman,

And a plurality of slave controllers are sequentially started in a time-division multiple access manner so that the slave controllers are not started at the same time by receiving a start request signal from the slave controller.
The method of claim 3,

The main fisherman,

Setting the number of slave controllers and generating a synchronization indicator signal that defines the startup sequence of the slave controllers so that the slave controllers can start sequentially; And

Sending a start response signal to start the slave control unit upon receiving a start request from the slave control unit according to the synchronization indicator signal;

Sequential start PWM control apparatus of the electric motor, characterized in that for sequentially starting the plurality of slave control unit in a time division multiple access method.
The method of claim 3,

The plurality of subordinate control unit,

Receiving synchronization indicator signals from the main controller;

Transmitting a start request signal to the main control unit after a time set by the synchronization indicator signal;

Controlling the inductive load to start up during the start time set by the synchronization indicator signal when receiving the start response signal from the main controller;

Sequential start PWM control device of the motor, characterized in that for starting sequentially by the time division multiple access method.