JP3402949B2 - Motor start / stop method by motor drive inverter device - Google Patents

Description

Detailed Description of the Invention

[0001]

The present invention relates to relates to start and stop process of the motor by the motor driving inverter equipment to smoothly start and stop the motor by multi-phase type inverter.

[0002]

2. Description of the Related Art FIG. 7 shows a conventional circuit diagram of a main circuit of a multi-phase type inverter device for driving an electric motor, and FIG. 8 shows its operation.

As shown in FIG. 7, when a high-voltage input power source is received and the frequency is controlled by an inverter device to drive a high-voltage large-capacity electric motor 6, the inverter device has a low rated voltage. An input transformer 01 for voltage drop is arranged.

Further, since the rated capacity of the inverter device 3A is also limited, a plurality of inverter devices 3A and 3B are provided.
Is required, and the output synthesis transformer 5A that doubles as a voltage booster,
5B is provided.

The input transformer 01 is composed of an input delta winding, an output star winding, and an output delta winding.

The high-voltage tap a of the output winding of the input transformer 01 is connected to the inverter device 3A, and the high-voltage tap b of the delta winding for output is connected to the inverter device 3B.

The inverter devices 3A and 3B are composed of rectifiers 9A and 9B, smoothing capacitors 8A and 8B, and output GTO (gate turn-off) inverters 10A and 10B.
It is composed by. Also, this GTO inverter 10
The A and 10B are PWM (pulse width modulation) controlled to control the output frequency, voltage and the like.

As shown in FIG. 7 , the output of the inverter device 3A is connected to the input delta winding of the output synthesizing transformer 5A, and the output of the inverter device 3B is connected to the input delta winding of the output synthesizing transformer 5B. Has been done.

Voltages whose phases are deviated from each other by 30 ° are inputted from the inverter devices 3A and 3B to the output synthesizing transformers 5A and 5B, respectively. The output voltage combined by the star winding is the sum of the output voltages of the inverter devices 3A and 3B. The combined output voltage is output to the large-capacity electric motor 6.

The inverter devices 3A and 3B are provided with cooling fans and electric motors (not shown) for cooling the rectifiers 9A and 9B, the GTO inverters 10A and 10B, and the electric motor 6 is started. For this purpose, the turning gear and the electric motor are connected via a clutch (not shown).

In the above structure, when the electric motor 6 is started, first, it is started by the turning gear and 1% of the rated frequency (0.6 H when the commercial frequency is 60 Hz).
Increase the rotation speed to about z).

After that, the clutch is disengaged and the speed is increased to the rated frequency by the inverter devices 3A and 3B.

At this time, as shown in FIG. 8, it is preferable that the minimum frequency at which the inverter devices 3A and 3B can operate is 5% or more of the rated frequency. The modulation degree increases in proportion to the frequency, but the DC intermediate voltage ratio and the maximum current ratio (torque) are 100%.

[0014]

The above-mentioned conventional device has the following problems. (A) The high DC intermediate voltage is constant, and the minimum modulation degree is determined by the constraint condition based on the establishment of the voltage vector of the voltage control by the PWM (pulse width modulation) control of the inverter.
That is, since the lowest frequency becomes a relatively high frequency in the GTO inverter controlled by PWM, (i) the torque is reduced at the time of starting or the overcurrent is generated, which may cause a failure in starting in a system having a large starting torque. .
(Ii) When the regenerative braking is performed at the time of stop to increase the speed of decrease in rotation, the effective rotational speed of the regenerative braking ends at a relatively high frequency and voltage, which causes the stop time to be extended. (B) In the low frequency region, the output voltage also decreases in proportion to the frequency, and the reactance of the electric motor 6 (which contributes to the starting torque) also decreases. However, since the output current is constant, the voltage drop due to the winding resistance of the output combining transformers 5A and 5B and the electric motor 6 becomes relatively large, and as a result, the electric power for starting the electric motor or the like to the load side decreases. ,
The start-up torque was reduced, resulting in failure of start-up and extension of start-up time. (C) Since the DC braking cannot be applied, the inverter device 3
Since the stop operation is performed by disconnecting the outputs of A and 3B, a great amount of time is required until the complete stop. (D) Further, in order to completely stop in a short time, it is necessary to use a mechanical brake together.

[0015]

Means for Solving the Problems The present invention is order to solve the above problems, is connected to the high pressure tap or a low pressure tap input transformer for voltage input side descending output side or output transformer via the output transformer the bypass using electric motive driving inverter device with an inverter device connected to the electric motor, to perform the start and stop of the electric motor
It was

In the above, when the motor is started, the input voltage is cut off.
More conversion, connecting the input side to the low pressure tap. Also on the output side
To bypass the output transformer and connect to the generator . Then, the inverter device inputs the low voltage, outputs alternating current of a constant current at a predetermined frequency increase, and drives the electric motor. Against the high pressure tap more input thereafter input voltage changeover
To continue . Also , connect the output side to the generator through the output transformer.
To continue . Then, the inverter device inputs a high voltage, outputs a constant current alternating current at a predetermined frequency increase,
After boosting the voltage with the output transformer, the electric motor is driven.

As described above, it is possible to quickly and smoothly start the electric motor with high reliability.

Input by switching the input voltage when the motor is stopped
Side high pressure tap, low pressure tap connection , output side output
The connection to the electric motor via the transformer or by bypass operates in the reverse order to decelerate the electric motor. Immediately before the stop, DC braking is applied by the inverter device to stop.

As described above, a highly reliable, low-loss electric motor can be stopped quickly and smoothly .

That is, the present invention is for driving the above electric motor.
Use the following method to start the motor using the inverter device.
As shown in (1). ( 1 ) Connect the input side to the low voltage tap, connect the output side to the electric motor by bypassing the output transformer, increase the output frequency of the inverter device, and then connect the input side to the high voltage tap and the output side to the output transformer. Connected to the electric motor via
Starting of the motor by the upper Symbol motor driving inverter apparatus, characterized in that to increase the output frequency of the inverter device.

In the above, at the time of starting, the input side is connected to the low-voltage tap by switching the input voltage, and the output side is bypassed with the output transformer and connected with the generator, so that the output frequency of the inverter device is gradually increased and the motor is driven. To start. When a predetermined frequency is reached, similarly, the input side is switched and connected to the high-voltage tap, and the output side is connected to the electric motor through the output transformer, and the frequency of the inverter device is sequentially increased to drive the electric motor to speed up. . Further, the present invention is for driving the above electric motor.
Use the following method to stop the motor using the inverter device.
As shown in (2). ( 2 ) The input side is connected to the high voltage tap, the output side is connected to the electric motor through the output transformer, the output frequency of the inverter device is reduced, high voltage deceleration operation is performed by regenerative braking, and then the input side is low voltage. Connect to the tap, connect the output side to the motor by bypassing the output transformer, reduce the output frequency of the inverter device and perform low voltage deceleration operation by regenerative braking, and then set the output of the inverter device to DC and stop DC braking. the method of stopping the motor by the electric motor driving inverter apparatus of the above SL which is characterized in that the operation.

[0022] In the above, stop, connects the I <br/> Ri input side to the input voltage changeover to the high pressure tap, and outputs tiger output side
The output frequency of the inverter device is gradually reduced by connecting the motor to the motor via the sensor, and the motor is decelerated. Similarly, when the specified frequency is reached, the input side is switched to the low voltage tap .
Electricity by connecting and bypassing the output transformer on the output side
When connected to the machine, the output frequency of the inverter device is gradually reduced and the electric motor is decelerated. After that, it becomes DC, and the motor is DC-braked.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention is shown in FIGS.
1 is a circuit diagram of the first embodiment of the present invention, and FIG. 2 is a circuit diagram of the output synthesizing transformer of the first embodiment.

FIG. 3 is a control flow chart at the time of starting the first embodiment,
FIG. 4 is an operation explanatory view of the first mode, and FIG. 5 is a control flow diagram when the first mode is stopped.

FIG. 6 is a circuit diagram of a second embodiment of the present invention.

In FIGS. 1 and 6, the same reference numerals as those in FIG. 7 are equivalent to conventional members. (Configuration of First Embodiment of the Present Invention) An embodiment of the present invention will be described with reference to FIGS.

As shown in FIG. 1, the high voltage input power source is received via the power switch 18, and the inverter device 3A,
When the frequency is controlled by 3B to drive the high-voltage and large-capacity electric motor 6, the inverter devices 3A and 3B are provided with the input transformer 1a for lowering the voltage because the rated voltage is low.

Further, output combining transformers 5A and 5B are provided for combining the outputs of the inverter devices 3A and 3B and increasing the output voltage to the rated voltage of the electric motor 6.

The inverter devices 3A and 3B have two sets, but the number of sets is determined according to the capacity of the electric motor 6, and if the capacity of the electric motor 6 is small, one inverter device may be used. On the contrary, if the capacity is larger, the number of inverter devices can be three or more depending on the capacity of the electric motor 6.

The input transformer 1a is composed of an input delta winding, an output star winding, and an output delta winding.

[0031] And in the delta winding for input, and is connected high voltage input power through a power switch 18. A high voltage tap a (voltage = HV) and a low voltage tap c (voltage = LV) are provided on the output star winding. The output delta winding has a high-voltage tap b (voltage = HV).
Is provided.

In the first embodiment, the voltage ratio HV /
Although the LV is set to 1/3, it is not limited to this.

The high voltage tap a and the low voltage tap c of the input transformer 1a are connected to the inverter device 3A via the high voltage input switch 2A and the low voltage input switch 2B of the input voltage switch 2, respectively.

The high voltage tap b of the input transformer 1a
Are connected to the inverter device 3B.

The high voltage input switch 2A and the low voltage input switch 2B are interlocked,
It is designed not to turn on at the same time.

Each of the inverter devices 3A and 3B has three sets of rectifiers 9A and 9B for full-wave rectification, smoothing capacitors 8A and 8B for smoothing the pulsating current from the rectifiers 9A and 9B, and a direct current (DC) 3.
Output GTO inverters 10A, 1 for converting to phase alternating current
It is composed of 0B.

Further, the inverter devices 3A and 3B include
In order to discharge the backflow power from the electric motor 6 when the electric motor 6 is stopped, the brakes 17A, 1 composed of resistors and rectifiers are provided.
7B is provided.

The GTO inverters 10A, 10B
The output frequency, voltage, etc. are controlled by PWM (pulse width modulation) control. In this PWM control, each inverter 10 is based on a modulated wave having the same frequency as the target frequency and a triangular carrier wave having a frequency equal to or higher than the modulated wave.
The switching of A and 10B is controlled, and the modulation factor, the number of pulses, the pulse width, and the output voltage of the inverter change in proportion to the target frequency.

A cooling fan and cooling fan motors 15A and 15B are provided in the inverter devices 3A and 3B, respectively. Furthermore, charging lines 16A and 16B are connected to the smoothing capacitors 8A and 8B. The cooling fan motors 15A and 15B and the smoothing capacitor 8
Electric power for charging A and 8B is supplied from the cooling fan driving / charging devices 14A and 14B.

The output of the inverter device 3A is supplied to the large capacity electric motor 6 via the bypass switch 4B of the output transformer bypass selector 4.

Further, the output of the inverter device 3A is the high voltage output switch 4 of the output transformer bypass selector 4.
A and the input delta winding of the output synthesis transformer 5A as shown in FIG.

On the other hand, the output of the inverter device 3B is as shown in FIG.
As shown in, the output synthesizing transformer 5B is connected to the input delta winding.

The output double-star winding of the output synthesizing transformer 5B is connected to one end of the output star winding of the output synthesizing transformer 5A, whereby the outputs of the two sets of inverter devices 3A and 3B are synthesized, and the output synthesis is performed. Transformer 5
The other end of the A output star winding wire is connected to a large-capacity electric motor 6 via a high voltage output switch 4C of the output transformer bypass selector 4.

The high voltage output switches 4A and 4C of the output transformer bypass selector 4 and the bypass switch 4 are provided.
B is interlocked so that it is not turned on at the same time.

The electric motor 6 is connected to the turning gear electric motor 13 via a clutch 13A. A rotation detector 7 is attached to the electric motor 6.

Then, in order to control each of the above-mentioned devices,
Start / stop control device 11, cooling fan drive / charging device 1
4A, 14B and a turning gear control device 12 are provided.

The start / stop controller 11 controls ON / OFF of the input voltage switch 2 and the output transformer bypass switch 4.

The start / stop control device 11 also controls the turning gear control device 12 and the cooling fan / charge control devices 14A and 14B.

Further, the start / stop control device 11 sends a switching signal of the inverters of the inverter devices 3A and 3B for PWM (pulse width modulation) control according to the target frequency.

The turning gear control device 12 controls driving of the turning gear motor 13 and engagement / disengagement of the clutch 13A.

Cooling fan drive / charging device 14A, 14B
Is composed of an inverter, a step-up transformer, and a rectifier, which are not shown.

Then, the cooling fan motors 15A and 15B
During the operation of 1, the rotational speed of the cooling fan motors 15A and 15B is controlled by the inverter. When the smoothing capacitors 8A and 8B are charged with a constant current, the charging lines 16A and 1A are charged by the inverter, the step-up transformer and the rectifier.
Charging is performed with a constant current via 6B . (Control of Startup of First Embodiment of the Present Invention) In the configuration described above, the startup of the electric motor 6 is controlled as shown in the control flow of FIG.

Control at startup is classified into three major steps.

That is, first, the mechanical drive device (turning gear or the like) is used to perform a slow speed starting process (step 2), and the low voltage inverter is started by a low voltage at a frequency of 0.6 Hz (1% of the rated speed). When the frequency finally reaches 6 Hz (10% of the rated speed), the input voltage is switched to a high voltage (rated voltage) and the rated voltage inverter starting process (step 4 ) is performed.

The details of each step 2, 3 and 4 will be described below.

First, before starting the start-up, the power switch 18 and all the switches 2A, 2B, 4A, 4B,
Confirm that 4C is off (step S1)
1).

Then, the start / stop control device 11 transmits a start start signal to the turning gear control device 12 and the cooling fan drive / charging devices 14A and 14B (step S12).

In the slow speed starting process of step 2, first, the turning gear control device 12 receives the starting signal and engages the clutch 13A (step S2).
1).

Then, the turning gear electric motor 13 is driven to start the electric motor 6, and the speed is increased for a predetermined time (T1) (step S22).

The predetermined time (T1) is the electric motor 6
Is calculated and set in advance based on the starting characteristics of

The rotation frequency of the electric motor 6 is the lowest frequency f ₁ = 0.
When the speed is increased to 6 Hz (1% of the rated frequency), the clutch 13A is disengaged and the turning gear motor 13 is released.
Is turned off, and a turning completion signal is transmitted to the start / stop control device 11 (step S23).

This completes the step 2 slow speed starting process.

On the other hand, in parallel with the slow speed starting process of step 2, the cooling fan drive / charging device 14A receives the starting signal and charges the smoothing capacitor 8A with a constant current (step S61).

In this charging, the voltage of the smoothing capacitor 8A and the inverter device 3A are set to the low voltage input switch 2B.
It ends when the voltage reaches the voltage (low voltage) when is turned on.

Further, in parallel with the slow speed starting process of step 2, the cooling fan driving / charging device 14B also receives the starting signal and charges the smoothing capacitor 8B with a constant current (step S62).

The charging is completed when the voltage of the smoothing capacitor 8B reaches the rated voltage.

Next, in the step of starting the reduced voltage inverter in step 3, the start / stop control device 11 receives the turning completion signal and, if necessary, the cooling fan.
After receiving the charge completion signal from the charge control devices 14A and 14B (the reception of each charge completion signal may be before the power switch 18 is turned on), the input voltage is changed in order to connect the input to the low voltage tap c side. The low voltage input switch 2B of the switch 2 is turned on, and further, the bypass switch 4B of the output transformer bypass switch 4 is turned on to bypass the output transformer 5 (step S31). Thereafter, the power switch 18 is turned on (step 32), and power feeding is started.

Then, a preset time schedule
Joule or electric motor from rotation detector 7 as required
The lowest frequency is used as a feedback signal
Number f ₁= 1.2Hz to switching frequency f₂= 6Hz (rating
Up to 10% of the frequency) by low voltage (LV)
Switching signal whose frequency increases for a predetermined time (T2)
Is transmitted to the inverter 10A (step S33), and the speed is increased.
Drive.

The voltage also rises in proportion to the frequency, but since the voltage is low, the DC intermediate voltage is 1/3 of the normal voltage as shown in FIG.

In this state, in order to obtain a normal output voltage ratio, the modulation degree is set to about three times the normal value (= HV / LV). Therefore, the maximum current ratio of the electric motor 6 to the rated current is suppressed to 150%.

Thereafter, the rotation detector 7 detects that the rotation speed has reached the switching frequency f ₂ = 6 Hz, and the power switch 18 is turned off for a predetermined time (T3) (step 3).
4), the low voltage input switch 2B of the input voltage switch 2 is turned off and the bypass switch 4B of the output transformer bypass switch 4 is also turned off (step S35).

This completes the step 3 of starting the reduced voltage inverter.

Further, during the predetermined time (T3), the cooling fan driving / charging devices 14A, 14B charge the smoothing capacitors 8A, 8B with a constant current (step S63,
Step S64) (Note that the charging may be started after step 34).

This charging is completed when the voltage of the smoothing capacitors 8A, 8B becomes the voltage (high voltage / rated voltage) when the high voltage input switch 2A of the inverter devices 3A, 3B is on.

In step 3, the inverter device 3
B is not movable, so ideally smoothing capacitor 8
B is still charged in step 62, and the charging work in step 64 is unnecessary.

However, if the period of step 3 is long, the charging voltage is lowered due to leakage, so that the charging is performed again. Therefore, if the period of step 3 is short, step 64 is unnecessary.

Next, the process proceeds to the step 4 of starting the rated voltage inverter.

The start / stop control device 11 receives a high voltage charging completion signal from the cooling fan driving / charging devices 14A and 14B as necessary after a predetermined time (T3) has passed (note that each charging completion signal To receive the power switch 1
8 may be turned on), in order to connect the input to the high voltage tap a side, the high voltage input switch 2A of the input voltage switch 2 is turned on.

Further, the high voltage output switches 4A and 4C of the output transformer bypass selector 4 are turned on to pass through the output synthesizing transformer 5A (step S41).

Thereafter, the power switch 18 is turned on to energize.

In the inverter devices 3A and 3B, the high frequency intermediate DC voltage of the smoothing capacitors 8A and 8B is switched on the basis of the rotation speed signal from the rotation detector 7, and the switching frequency f ₂ (minimum modulation degree) is set in a predetermined pattern. ) Is output to increase the operating frequency to perform the speed-up operation (step S43).

In this case, as shown in FIG. 4, the DC intermediate voltage and the maximum current ratio are 100%, and the modulation degree is normal.

The electric motor 6 includes output combining transformers 5A and 5B.
The AC power is received via the motor, the rotation is increased according to the input, the operating state is set, the startup is completed, and the normal operation is performed (step S5).

As described above, the electric motor 6 can be started quickly and smoothly.

The cooling fan drive / charging device 14A,
In 14B, the high voltage switching completion signal is received from the start / stop control device 11, and the cooling fan motors 15A and 15B are received.
And the frequency control are started (steps S65 and S6).
6) (Note that this operation may be started after step 42).

This frequency corresponds to the inverter device 3A,
It is controlled according to the temperature of the 3B inverters 10A and 10B.

If the smoothing capacitors 8A and 8B do not need to be charged, steps S61, S62, S63 and S are performed.
The control of 64 and S65 can be omitted.

Further, the charging voltage to the smoothing capacitors 8A and 8B does not need to be strictly adjusted to the voltage during operation of the GTO inverters 10A and 10B. That is, it is sufficient to charge the power switch 18 to a voltage that can prevent an excessive current when the power switch 18 is turned on.
It may be ± 30 to 40%.

Further, the cooling fan motors 15A and 15B
When the rotation speed control is not performed (that is, constant rotation operation ) , the control in steps S64 and S65 simply turns on the power switch. (Control of Stop of First Embodiment of Present Invention) Next, the stop of the electric motor 6 is performed as shown in the control flow of FIG.

The control at the time of stop is classified into three large steps.

That is, first, the high voltage deceleration process by regenerative braking is performed by the two sets of inverter devices 3A and 3B at high voltage (step 7), and when the frequency reaches 3 Hz (5% of the rated speed), the inverter is turned on. A low voltage deceleration process by regenerative braking is performed by the device 3A (step 8 ), and finally when the frequency reaches 1.2 Hz (2% of rated speed), a DC braking deceleration process by the inverter device 3A (step 9) is performed. Stop.

The details of steps 7 to 9 will be described below.

First, a stop start signal is transmitted manually or the like (step 6).

In the high voltage deceleration process (step 7), the start / stop control device 11 changes the operating frequency (60 Hz) to the switching frequency f ₃ (3H) according to the stop pattern.
In order to reduce the frequency and voltage to z) with time, the signal from the rotation speed detector 7 is used as a feedback signal to reduce the modulation degree when a high voltage is input.

Then, the switching signals of the inverters 10A and 10B of the inverter devices 3A and 3B are transmitted according to the modulation degree (step S71).

That is, the output frequencies of the inverter devices 3A and 3B are lowered so that the slip of the induction motor 6 becomes negative.

Then, the electric motor 6 generates electric power according to the slip. This generated electric power is the inverter device 3A,
It is returned to 3B and consumed by the resistors of the brakes 17A and 17B in the inverter devices 3A and 3B.

In this way, the electric motor 6 is decelerated by regenerative braking at a high voltage.

The signal from the rotation speed detector 7 is 3H.
It is detected that z is equal to or less than z (step 72), and the process proceeds to the next low voltage deceleration process (step 8).

In the low voltage deceleration process (step 8), first, the power switch 18 is turned off (step 8).
1).

After that, the cooling fan drive / charging device 14B
Then, the smoothing capacitor 8B is charged with a constant current (step S67). This charging ends when the voltage of the smoothing capacitor 8B becomes the same as the voltage (high voltage / rated voltage) of the inverter device 3A when the high voltage input switch 2A is on. Then, the operation of the inverter device 3B ends. Further, the operation of the cooling fan electric motor 15B by the cooling fan driving / charging device 14B is also stopped.

Then, by the start / stop control device 11,
In order to switch the input to the low voltage tap side, the high voltage input switch 2A and the high voltage output switches 4A and 4C are turned off, and then the low voltage input switch 2B and the bypass switch 4B are turned on (step S82).

After that, and also after receiving a high voltage charging completion signal from the cooling fan drive / charging device 14B as required, the power switch 18 is turned off (step 83).

The start / stop controller 11 changes the operating frequency (3 Hz) from the switching frequency f according to the stop pattern.
_In order to reduce the frequency and voltage to ₄ (1.2 Hz) with time, the signal from the rotation speed detector 7 is used as a feedback signal to reduce the modulation degree at a low voltage input.

Then, the switching signal of the inverter 10A of the inverter device 3A corresponding to the modulation degree is transmitted (step S84).

That is, the output frequencies of the inverter devices 3A and 3B are lowered so that the slip of the induction motor 6 becomes negative.

Then, the electric motor 6 generates electric power according to the slip. The generated power is returned to the inverter device 3A and consumed by the resistor of the brake 17A in the inverter device 3A.

In this way, the electric motor 6 is decelerated by regenerative braking at a low voltage.

The signal from the rotation speed detector 7 is 1.
Detecting that the frequency is below 2Hz (step 85),
The process proceeds to the next DC braking process (step 9).

In the DC braking process (step 9), the start / stop control device 11 controls the inverter 10A of the inverter device 3A to perform the DC braking operation.

That is, a DC voltage (or,
A low-frequency rotating magnetic field is applied to the stator of the electric motor 6 to generate a non-rotating magnetic field (or a low-frequency rotating magnetic field rotating in reverse). Then, a short-circuit current flows through the rotor of the electric motor 6,
Braking force is generated.

In this way, the frequency is switched to the switching frequency f.
_The brake is applied from ₄ (1.2 Hz) to 0 (step S92).

Thus, the stop of the electric motor 6 is completed quickly and smoothly by the DC braking (step S10).

As described above, starting the large-capacity electric motor 6
Outages are quick and smooth with low loss. (Configuration of Second Embodiment of the Present Invention) Second Embodiment of the Present Invention
The form will be described with reference to FIG.

In FIG. 6, the same reference numerals as those in FIG. 1 are equivalent components to those of the first embodiment of the present invention.

The second embodiment of the present invention is different from the first embodiment in that the electric motor 6 is equal to or less than the rated capacity of the inverter device 3A, and therefore the inverter device 3A, the cooling fan and the electric motor 15A, and the cooling fan. The driving / charging device 14A is one set.

Therefore, the input transformer 1b has only one output winding, and the output transformer 5 is merely a step-up transformer. (Control of Second Embodiment of Present Invention) Second Embodiment of Present Invention
The start / stop control of the embodiment is carried out by implementing the present invention shown in FIGS. 3 and 5 except that the inverter device 3A, the cooling fan and the electric motor 15A, and the cooling fan driving / charging device 14A are one set. The same control as the start / stop control of the first mode is performed.

That is, the steps S62, S64, and S66 are unnecessary in the control at the time of startup shown in FIG.

Further, in the control at the time of stop shown in FIG. 5, steps S67 and S68 are unnecessary.

As described above, one set or two sets of the inverter device, the cooling fan and the electric motor, and the cooling fan driving / charging device are provided.
Although the form of the set has been described, the present invention is not limited to this, and is similarly applicable to the case of three or more sets.

Further, in each of the embodiments, since the power switch 18 is turned on / off each time the switch is made, the switches of the input voltage switch 2 and the output transformer bypass switch 4 are inexpensive contactless switching contactors. , Disconnector, contact, etc. can be adopted.

As described above, each embodiment has the following effects. Torque drop at startup and overcurrent are eliminated. By switching taps between the high voltage side and the low voltage side, it is possible to avoid the restriction on the minimum modulation degree of the inverter, and it is possible to smoothly and swiftly start the variable frequency according to the motor characteristics. By switching taps between the high voltage side and the low voltage side, the minimum modulation factor restriction of the inverter can be avoided, regenerative braking can be performed up to a low frequency and voltage, and smooth and quick deceleration operation that matches the characteristics of the motor becomes possible. Further, by switching the taps on the low voltage side, it is possible to stop the electric motor due to DC braking. By using a plurality of two inverters and an output combining transformer, it is possible to start, operate, and stop even a large-capacity electric motor that cannot be stopped or started with only one inverter.

[0123]

As described above, the present invention has the following effects. (A) Regenerative braking of the electric motor is possible, and smooth and rapid stop and start can be performed with low loss. (B) By switching the taps between the high voltage side and the low voltage side, the restriction on the minimum modulation degree of the inverter can be avoided, and smooth and quick variable frequency stop start can be performed according to the motor characteristics. (C) The inverter is effectively cooled according to the operation (heat generation).

[Brief description of drawings]

FIG. 1 is a circuit diagram of a first embodiment of the present invention.

FIG. 2 is a circuit diagram of an output synthesizing transformer section of the first embodiment.

FIG. 3 is a control flow diagram at the time of startup of the first embodiment.

FIG. 4 is an operation explanatory view of the first embodiment.

FIG. 5 is a control flow chart at the time of stop of the first embodiment.

FIG. 6 is a circuit diagram of a second embodiment of the present invention.

FIG. 7 is a circuit diagram of a conventional example.

FIG. 8 is a diagram for explaining the operation of the conventional example.

[Explanation of symbols]

1a, 1b, 01 Input transformer 2 Input voltage switch 2A High voltage input switch 2B Low voltage input switch 3A, 3B inverter device 4-output transformer bypass switch 4A, 4C High voltage output switch 4B bypass switch 5 output boost transformer 5A, 5B output synthesis transformer 6 electric motor 7 Rotation detector 8A, 8B smoothing capacitor 9A, 9B rectifier 10A, 10B GTO inverter 11 Start / stop control device 12 Turning gear controller 13 Turning gear motor 13A clutch 14A, 14B Cooling fan drive / charging device 15A, 15B Cooling fan motor 16A, 16B charging line 17A, 17B brake 18 power switch a High voltage tap (voltage = HV) b High voltage tap (voltage = HV) c Low voltage tap (voltage = LV)

Claims (2)

(57) [Claims] 1. A is connected to the high pressure tap or a low pressure tap input transformer for input side voltage drop, the output-side motive collector equipped with an inverter apparatus connected to the motor, bypassing the in or output transformer via an output transformer Connect the input side to the low-voltage tap using the drive inverter device
The output side bypasses the output transformer and connects to the electric motor
Increase the inverter output frequency, and then
Connect the output side to the high voltage tap, and connect the output side to the output transformer.
Connected to the motor to increase the output frequency of the inverter device.
Inverter device for driving a motor characterized by being added
How to start the electric motor . 2. A high voltage of an input transformer for a voltage drop on the input side.
Connected to the tap or low pressure tap, and the output side
Motorized through the output transformer or bypassing the output transformer
For driving a motor equipped with an inverter device connected to the machine
Input side to high-voltage tap using converter device
And connect the output side to the motor via the output transformer,
By reducing the output frequency of the inverter device and regenerative braking
Perform high voltage deceleration operation, and then connect the input side to the low pressure tap.
The output side, bypass the output transformer and connect to the motor.
Continue to regenerate by reducing the output frequency of the inverter device
Low voltage deceleration operation is performed, and then the inverter device
The feature is that the output of DC is set to DC and DC braking stop operation is performed.
Stopping the motor by the inverter device for driving the motor
Way .