JP5399789B2 - Inverter device and teaching method for inverter device - Google Patents

Description

  The present invention relates to the inverter device used in a motor drive system including an inverter device that performs variable speed control of a motor by an inverter circuit, and a mechanical brake that stops rotation of the motor, and a teaching method for the inverter device.

  A motor drive system including a mechanical brake for stopping rotation of a motor is applied to various uses such as an electric hoist and a crane. In such a motor drive system, there is a problem of how to determine the operation timing of the brake. When driving a motor via an inverter circuit, the output frequency of the inverter device is increased to about 2 to 3 Hz, for example, by utilizing the function of detecting the speed and current of the inverter device, and the output current of the inverter device When the current exceeds the specified current, the brake is opened. Further, when the brake is closed, a low speed command is given to the inverter device, and the brake is closed at the time of deceleration until the output frequency is sufficiently lowered.

  At this time, it is necessary to operate the brake while maintaining a low output frequency at which the output torque of the motor can resist the load torque. However, the mechanical brake actually starts from the time when the control command for opening and closing is given. There is a delay time of about several tens of milliseconds to a hundred milliseconds before the brake is applied. Therefore, when the brake is closed, a period in which the brake does not act on the motor occurs if the output of the inverter device stops within the delay time. Therefore, it is necessary to adjust the control sequence in consideration of the delay time of the mechanical brake. In addition, since the preconditions of the drive system differ depending on the type of motor used, the type of load, etc., these adjustments must be made individually.

Therefore, in Patent Document 1, a technique for executing a sequence for teaching the delay time when the brake is opened and the delay time when the brake is closed for each actual system, and using the data obtained as a result for the subsequent brake control. Is disclosed. The teaching sequence of the brake closing delay time in Patent Document 1 is performed according to the procedure shown in FIG.
As shown in FIG. 7E, when an operation stop command is given (time t1), the motor starts decelerating (see (a)). When the output frequency of the motor reaches a preset creep frequency (holding frequency) (time t2), a close signal is output to the mechanical brake (see (c)) and measurement of the brake close delay time is started. To do. The mechanical brake is actually closed at time t3 when the delay time Tmc has elapsed from time t2 (see (d)).

  When the brake is closed, the actual speed of the motor becomes substantially zero, and the output torque of the motor starts to increase as a result of feedback control according to the difference from the creep frequency (see (b)). When the output torque becomes equal to or greater than the threshold, it is determined that the brake is closed (time t4), and the interval between times t2 and t4 is recorded as the brake closing delay time Tc. Therefore, at times t3 to t4, there is an error between the delay time Tc obtained by teaching and the actual delay time Tmc.

JP 2006-345602 A

However, the delay time Tc obtained by teaching as described above has the following problems.
(1) When teaching is performed with a crane or the like accompanied by a load, the brake closing delay time Tc tends to be shorter than the actual delay time Tmc.
(2) When teaching is performed with a crane or the like having no load or a light load, the brake closing delay time Tc tends to be longer than the actual delay time Tmc.

  Hereinafter, these will be described more specifically. FIG. 8 shows an example of teaching when a load of 60% is applied to the motor rating. The threshold for determining “brake closing” is set to 50% of the rating, and the actual delay time Tmc is 100 ms. The motor rotates at the creep frequency from when the brake closing signal is given until the brake is actually operated, but the output torque during that period substantially matches the load torque. Therefore, in this case, a torque with a rating of 60% is required.

  Then, when the motor is decelerated to reach the creep frequency and shifts to constant speed operation, the output torque of the motor changes from the deceleration torque to the load torque. Therefore, when shifting to constant speed operation, the output torque exceeds the threshold value (rated value of 50%), and the teaching operation is immediately terminated. As a result, in the example shown in FIG. 8, the delay time Tc is 10 ms. Since it is assumed that the control is performed using the delay time Tc = 10 ms obtained by this teaching (Tc << Tmc), the motor stops before the brake is actually closed, so that “load deviation” may occur. There is.

  FIG. 9 is an example of teaching in the case of no load, and the threshold for determining “brake closing” and the actual delay time Tmc are the same as those in FIG. In this case, when the brake is actually operated, the output torque of the motor starts to rise from the zero level corresponding to the no load. Therefore, the time until the threshold value is exceeded becomes longer, and in this example, the delay time Tc = 240 ms. In this way, the case of (Tc >> Tmc) is not a problem from the viewpoint of safety, but if the error becomes too large, for example, when performing inching operation at a short interval as described below, overcurrent protection is activated and the work is performed. It is assumed that this will cause problems.

In FIG. 10, it is assumed that the delay time Tc = 500 ms obtained by teaching is compared to the actual delay time Tmc = 100 ms. The brake closes at time t1 when 100 ms elapses after the brake close signal is given, but the inverter recognizes that the delay time is 500 ms, so the brake is not yet closed and operation at the creep frequency is continued. To do. When an acceleration operation signal is given at the time t2 during the operation, the motor is accelerated on the inverter side. However, since the brake is already closed, the energization current increases and increases to the vicinity of the overcurrent limit threshold.
Thereafter, when the inching operation is repeated with a short cycle, the energization current fluctuates in the vicinity of the threshold value while the brake is closed, which may lead to an overcurrent protection operation. In order to avoid falling into such an operation state, it is necessary to further improve the accuracy of teaching.

  The present invention has been made in view of the above circumstances, and an object thereof is to obtain a more accurate result when performing a teaching operation for obtaining a brake closing delay time for a motor drive system including a mechanical brake. It is an object to provide an inverter device and a teaching method for the inverter device.

In order to achieve the above object, an inverter device according to claim 1 is used in a motor drive system including an inverter device that performs variable speed control of a motor by an inverter circuit, and a mechanical brake that stops rotation of the motor. In the device
A variable speed control of the motor, and a control unit for controlling the opening and closing of the brake;
When the control unit performs the brake closing control executed when the motor is stopped in conjunction with the variable speed control of the motor, the control unit performs the brake closing control based on the internal information of the control unit. Setting means for setting brake control data to be used,
The setting means, when setting the brake control data, from a state where the motor is rotating,
A command is given to the control unit to reduce the rotation frequency of the motor to a predetermined holding frequency,
When the rotation frequency of the motor reaches the holding frequency, the holding frequency is maintained for a predetermined holding time, during which the output torque of the motor is detected,
A value obtained by adding a predetermined increase to the detected output torque is set as a determination torque value,
When the closing command is output to the brake, measurement of the brake closing delay time is started,
The time until the output torque of the motor becomes equal to or greater than the determination torque value is measured as the brake closing delay time, and the time is recorded.

  As described above, the output torque when the motor is rotated at a constant speed at the holding frequency is substantially equal to the load torque. Therefore, if it is determined that the brake is in a closed state using a determination torque value obtained by adding a predetermined increase to the output torque detected during the constant speed rotation period, the brake close delay time can be more accurately set than before. Can be measured.

  According to the inverter device of the first aspect, since the brake close delay time closer to the true value can be measured in teaching, the brake close control is performed when the rotation of the motor is stopped using the brake close delay time. By doing so, the control can be completed in a short time. In addition, it can be avoided that the output current is increased and the overcurrent protection function is activated.

This is an example when applied to an electric hoist, and is a flowchart showing a teaching process for a brake closing delay time Tc. Timing chart corresponding to the teaching process of FIG. The figure which shows an example (in the case of no load) of each signal waveform observed in the teaching process of FIG. Fig. 3 equivalent when the rated load is 60% Functional block diagram mainly showing the configuration of the inverter device built in the hoist body (A) is a front view explaining the schematic structure of an electric hoist, (b) is the side view FIG. 2 equivalent diagram showing the prior art 4 equivalent diagram 3 equivalent figure Timing chart when the inching operation is repeated in a short cycle when the error of the brake close delay time obtained by teaching is large

  Hereinafter, an embodiment when applied to an electric hoist will be described with reference to FIGS. Fig.6 (a) is a front view explaining schematic structure of an electric hoist, (b) is a side view. The electric hoist 1 travels along the traveling rail 4 when the driving wheels 5 and 6 sandwiching the traveling rail 4 are driven by the two traveling motors 2 and 3. When the user operates a lifting switch (not shown), the hoisting motor 7 is driven so that the wire rope 8 is wound or unwound and the load (not shown) suspended from the hook 9 is lifted or lowered. It has become.

FIG. 5 is a functional block diagram mainly showing the configuration of the inverter device 11 built in the hoist body 10. An AC power supply 12 is supplied to the inverter device 11, and an inverter control unit 13 built in the inverter device 11 supplies a hoisting motor 7 constituted by a three-phase induction motor via an inverter circuit 14. It is configured to be controlled and driven.
The inverter control unit 13 includes a microcomputer, and includes a vector control unit 15, a brake control unit 16, an automatic setting function unit (setting means) 17, and the like. These blocks are mainly realized by software. An operation command, a frequency command, a teaching command, and the like are given to the inverter device 11 from the outside, and the inverter control unit 13 performs a vector control calculation by the vector control unit 15 based on these commands, A PWM signal is generated and output to the inverter circuit 14.

  The inverter control unit 13 controls the opening and closing of a mechanical brake (BR) 18 for restraining the shaft of the motor 7 when starting or stopping the hoisting motor (hereinafter simply referred to as a motor) 7. Control is performed by the unit 16 via the brake excitation unit 19. The brake control unit 16 performs opening / closing control of the brake 18 based on the brake control data 20. As will be described later, the brake control data 20 is automatically set by its action when a teaching command is given from the outside to cause the automatic setting function unit 17 to function. Further, when the automatic setting function unit 17 is not functioned, the setting data stored in advance in the memory (storage means) 21 is read and used.

  The vector control unit 15 detects currents of at least two phases (for example, u and w) via the inverter circuit 14 and performs vector control calculation based on the detected currents (sensorless vector control). When the current to be detected is only two phases, the remaining one phase (v) is obtained by calculation. Then, the rotational angular frequency ω, rotational phase angle θ, excitation current Id, torque current Iq, etc. of the motor 7 are calculated. The automatic setting function unit 17 obtains the rotational angular frequency ω and the torque current Iq from the vector control unit 15 when the brake control data 20 is automatically set.

  Next, the operation of this embodiment will be described with reference to FIGS. The teaching of the brake opening delay time is the same as that of Patent Document 1. In this embodiment, when the brake closing control is performed from the state where the motor is subsequently rotated, the teaching of the brake opening delay time is measured. The procedure will be described. FIG. 1 is a flowchart showing processing when the automatic setting function unit 17 of the inverter control unit 13 performs teaching for the brake closing delay time Tc when a teaching command is given from the outside. FIG. 2 is a diagram corresponding to FIG. 7 corresponding to the processing of FIG.

  When operation stop is commanded from the state in which the motor 7 is performing normal operation (step S1: YES, FIG. 2: t1), the automatic setting function unit 17 gives a frequency command fc to be given to the vector control unit 15, for example, The creep frequency (holding frequency) corresponding to the rated slip frequency (for example, about 2 Hz to 3 Hz) is set (step S2). When it is confirmed that the rotation frequency of the motor 7 is equal to or lower than the creep frequency (step S3: YES, FIG. 2: t2), the measurement of the creep holding time Th for keeping the rotation of the motor 7 at the creep frequency is performed. Start (step S4).

  In the next step S5, until the creep holding time Th becomes equal to or longer than a predetermined set value (for example, 200 ms) (NO, FIG. 2: t2 to t3), the process returns to step S4, and the output torque of the motor 7 is set at a predetermined interval. And measure the average value. As the output torque here, the automatic setting function unit 17 measures the torque current Iq (estimated torque) of the motor 7 from the vector control unit 15. For example, a primary delay time of 2 ms (corresponding to the sampling period) is added to the measurement of the torque current Iq, and the average is sequentially obtained by adding the latest measured value and the measured value of the previous period and multiplying by 1/2. The value at the time when the creep holding time Th has elapsed is defined as the final average value Torq.

  When the creep retention time Th elapses (step S5: YES), the average value Torq of the output torque is recorded by writing it in the memory 21 (step S6). Then, a brake close command is output to the brake control unit 16 (FIG. 2: t3), and measurement of the brake close delay time Tc is started (step S7). Then, the mechanism of the brake 18 starts transition from the open state to the closed state.

  Subsequently, the automatic setting function unit 17 acquires the torque current Iq of the motor 7 in the same manner as described above, and determines whether or not the output torque of the motor 7 is equal to or greater than the determination value (step S8). Here, the determination value (determination torque value) is obtained by adding, for example, 10% (predetermined increase) of the rated torque of the motor 7 to the average value Torq of the output torque recorded in step S6. While the output torque does not exceed the determination value (NO), the measurement of the brake closing delay time Tc is continued (step S12), and it is monitored whether or not the time Tc being measured is equal to or more than a preset upper limit value ( Step S13). If the upper limit value is not exceeded (NO), the process returns to step S8, and if the upper limit value is exceeded (YES), it is determined that there is an abnormality and the user is notified (step S14).

  When the true value Tmc of the brake closing delay time elapses at time t4 shown in FIG. 2, the brake 18 is actually closed and acts on the motor 7, and the output torque starts increasing. In step S8, when the output torque exceeds the determination value (YES, FIG. 2: t5), the automatic setting function unit 17 records the brake closing delay time Tc at that time (step S9) and ends the teaching operation. At the same time (step S10), the driving of the motor 7 by the vector control unit 15 and the inverter circuit 14 is also terminated (step S11).

  FIG. 3 shows an example of operation when teaching is performed in a no-load state. When the creep retention time Th = 200 ms and the brake closing delay time true value Tmc = 100 ms, the measured brake closing delay time Tc = 110 ms, and the error is 10%. FIG. 4 is an example of operation when teaching is performed in a state where the rated load is 60%. The others are the brake closing delay time Tc = 120 ms measured under the same conditions as FIG. 3, and the error is 20%. It has become.

  As described above, according to the present embodiment, the inverter 7 controls the motor 7 at the variable speed, and the inverter control unit 13 that controls the opening and closing of the brake 18, and the inverter control unit 13 is started or stopped. The brake control data used to perform the opening / closing control of the 18 brake executed in cooperation with the variable speed control of the motor 7 is based on internal information such as the torque current Iq and the rotational angular velocity ω of the inverter control unit 13. The inverter device 11 is configured to include an automatic setting function unit 17 that automatically sets.

Then, when the rotational frequency of the motor 7 is lowered to a predetermined creep frequency, the creep frequency is maintained for the creep holding time Th, during which the output torque of the motor 7 is detected to determine the average value Torq, and the average value Torq When 10% of the rated torque plus 10% of the rated torque is set as the determination torque value and the brake close command is output, measurement of the brake close delay time Tc is started, and the output torque of the motor 7 becomes equal to or greater than the determination torque value. Is measured as the brake closing delay time Tc, the time Tc is recorded.
Therefore, the brake close delay time Tc can be measured with higher accuracy than in the past, and if the brake close control is performed when the rotation of the motor 7 is stopped using the brake close delay time Tc, Control can be completed in a short time. In addition, it can be avoided that the output current is increased and the overcurrent protection function is activated.

The present invention is not limited to the embodiments described above and shown in the drawings, and the following modifications or expansions are possible.
When obtaining the average value of the output torque, the average value is not limited to the one in which the first order lag time is set and the average is sequentially taken. The output torque obtained during the creep holding time Th is sequentially stored, and the creep holding time Th is obtained. The average value may be obtained in a lump after the elapse of time.
Further, when the output torque hardly fluctuates, it is not always necessary to obtain the average value.
The determination of the determination value is not limited to adding 10% of the rated torque, and a predetermined increase in exception may be added.
The abnormality handling process may be performed as necessary.
The present invention is not limited to an electric hoist, but can be widely applied to a system that uses a mechanical brake such as a crane or an elevator and controls the opening and closing of the brake using an inverter output.
The motor is not limited to an induction motor, and may be a permanent magnet type motor such as a brushless DC motor.

  In the drawings, 7 is an induction motor, 11 is an inverter device, 13 is an inverter control unit, 14 is an inverter circuit, 17 is an automatic setting function unit (setting means), 18 is a mechanical brake, and 21 is a memory (storage means). .

Claims (2)

In the inverter device used in a motor drive system comprising an inverter device for variable speed control of a motor by an inverter circuit, and a mechanical brake for stopping the rotation of the motor,
A variable speed control of the motor, and a control unit for controlling the opening and closing of the brake;
When the control unit performs the brake closing control executed when the motor is stopped in conjunction with the variable speed control of the motor, the control unit performs the brake closing control based on the internal information of the control unit. Setting means for setting brake control data to be used,
The setting means, when setting the brake control data, from a state where the motor is rotating,
A command is given to the control unit to reduce the rotation frequency of the motor to a predetermined holding frequency,
When the rotation frequency of the motor reaches the holding frequency, the holding frequency is maintained for a predetermined holding time, during which the output torque of the motor is detected,
A value obtained by adding a predetermined increase to the detected output torque is set as a determination torque value,
When the closing command is output to the brake, measurement of the brake closing delay time is started,
An inverter device, wherein a time until the output torque of the motor becomes equal to or greater than the determination torque value is measured as the brake closing delay time, and the time is recorded. In a motor drive system comprising an inverter device for variable speed control of a motor by an inverter circuit and a mechanical brake for stopping the rotation of the motor, the brake is controlled when the brake is closed as the motor is stopped. A teaching method for measuring a brake closing delay time from when a closing command is output to when it is detected that the brake is actually closed,
From the state where the motor is rotating,
Reducing the rotational frequency of the motor to a predetermined holding frequency;
When the rotation frequency of the motor reaches the holding frequency, the holding frequency is maintained for a predetermined holding time, during which the output torque of the motor is detected,
A value obtained by adding a predetermined increase to the detected output torque is set as a determination torque value,
When the closing command is output to the brake, measurement of the brake closing delay time is started,
A teaching method for an inverter device, wherein a time until the output torque of the motor becomes equal to or greater than the determination torque value is measured as the brake closing delay time.

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