CA1180375A - Method for synchronizing a current-rectifying synchronous motor with a mains-supply - Google Patents
Method for synchronizing a current-rectifying synchronous motor with a mains-supplyInfo
- Publication number
- CA1180375A CA1180375A CA000409919A CA409919A CA1180375A CA 1180375 A CA1180375 A CA 1180375A CA 000409919 A CA000409919 A CA 000409919A CA 409919 A CA409919 A CA 409919A CA 1180375 A CA1180375 A CA 1180375A
- Authority
- CA
- Canada
- Prior art keywords
- mains
- motor
- converter
- frequency
- voltage
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P1/00—Arrangements for starting electric motors or dynamo-electric converters
- H02P1/16—Arrangements for starting electric motors or dynamo-electric converters for starting dynamo-electric motors or dynamo-electric converters
- H02P1/46—Arrangements for starting electric motors or dynamo-electric converters for starting dynamo-electric motors or dynamo-electric converters for starting an individual synchronous motor
- H02P1/52—Arrangements for starting electric motors or dynamo-electric converters for starting dynamo-electric motors or dynamo-electric converters for starting an individual synchronous motor by progressive increase of frequency of supply to motor
Abstract
ABSTRACT OF THE DISCLOSURE
The invention relates to a method for synchronizing a current-rectifying synchronous motor, with a mains-supply, through a frequency-converter, the mains and motor being at approximately the same frequency.
Pulses are taken from the mains-voltage through a trigger-stage and are compared with corresponding pulses from a rotating-field recognition-system of the motor in a logic circuit. In the in-phase condition, the pulses taken from the mains-voltage are connected in order to control the valves on the motor-current rectifier, and the pulses taken from the recognition-system are suppressed. At the same time the voltage in the direct-current intermediate circuit is adjusted, through the mains current-rectifier, to a fixed value, after which a synchronizing switch is closed.
The invention relates to a method for synchronizing a current-rectifying synchronous motor, with a mains-supply, through a frequency-converter, the mains and motor being at approximately the same frequency.
Pulses are taken from the mains-voltage through a trigger-stage and are compared with corresponding pulses from a rotating-field recognition-system of the motor in a logic circuit. In the in-phase condition, the pulses taken from the mains-voltage are connected in order to control the valves on the motor-current rectifier, and the pulses taken from the recognition-system are suppressed. At the same time the voltage in the direct-current intermediate circuit is adjusted, through the mains current-rectifier, to a fixed value, after which a synchronizing switch is closed.
Description
This invention relates to a method for synchronizing a frequency converter-synchronous motor having a three-phase mains supply through a partial converter including a mains converter and motor converter connected together by a direct-current intermediate circui-t and in which devices are used to detect frequency and phase posltions of-the motor and mains.
In three-phase drives for ships it is known to use synchronous motors fed through frequency converters for driving the propellers, whereby the frequency converter must be designed for the entire range of r.p.m. adjust-ments to the motor. Drives of this kind have the disadvantage, however, of being inefficient under partial load and of requiring additional space, additional commutating reactive power and considerable additional expense for the frequency converter.
A high-speed synchronizing method is disclosed in the Japanese patent application 5~-87 521, Abstract E-5~, April 28, 1981, Vol. 5/No. 63, wherein the mains and motor voltages are compared. As long as there are frequency deviations a signal Af is guided to a controller 15 which supplies a higher or lower voltage corresponding to the difference to the synchronous motor via a frequency converter. If the frequency is then equalized, a further signal Sy is then given by the frequency comparison device to a phase comparison device which detects phase differences between the mains and motor voltages and sends a corresponding signal ~ to a correction controller. The signal Sy is simultaneously applied to the controller 15, ensuring that it cannot transmit any further signals changing the speed of the motor. Following the phase equalization, the motor can be switched to the a.c. line.
If the frequency of the prime-mover, for example a Diesel engine, is freely adjustable, it is possible to use an electric shaft which is an arrange-ment in which the prime mover is connected to the propeller shaft by means of i'3'75 a 3-phase a]ternator and a 3-phase motor. Motor speed is controlled by prime mover speed. An electric shaft operates with high efficiency,but it can util-ize only the range of r.p.m. adjustment of the prime mover. In the r.p.m.
range below this, the synchronous motor can start up only asynchronously at a low torque. If the prime mover is a turbine, a high starting torque may be achieved by the use of a separate starting circuit which requires braking of the turbine by means of braking resistances. Here agaill, however, steady operation in the low r.p.m. range is also impossible.
In the work by K. KRANERT "Gasturboantriebe mit elektrischer Welle fuer eisbrechende Tanker", Jahrbuch der Schiffbautechnischen Gesellschaft, Vol. 72, pages 261 to 276, it is proposed to combine the good efficiency of the electric shaft and the good torque behaviour and r.p.m.-adjustment capability of the frequency-converter drive, by the use of a partial frequency-converter. Instead of asynchronous starting of the synchronous motor, this provides for starting with a partial frequency-converter which is a frequency-converter designed for use up to approximately only 40% of nominal voltage and is, therefore, substantially smaller than a complete frequency-converter and it permits torque-shocks and any steady engine r.p.m. If a change-over is made from frequency-converter drive to electric-shaft drive, mains, generator and motor voltages must be synchronized and, thereafter, a synchronizing switch must be closed.
With this known method, successful synchronization is impossible if the motor is loaded or unloaded by a sudden changein torque during the time elapsing between the release of the switching command and the actual closing of the switch (switching time constant). The engine r.p.m. control cannot maintain the momentary r.p.m. because of unavoidable time-constants.
In the e~treme case, the phase positions of the motor and mains voltages run 3'~,5 so far apart that incorrect synchronization may arise when the synchronizing switch is closed. The electric shaft drops out of step, resulting in high compensating currents which may lead to destruction o~ the installation.
It is therefore the purpose of the invention to provide a met~od of tlle type stated in the first paragraph which will ensure the change-over, within an acceptable time, from frequency-converter drive to electric shaft drive - in other words synchronization - even under power impulses (load shocks).
According to a broad aspect of the present invention the method is characterized in that until an approximate in-phase condition of mains and motor voltages is reached, the motor is externally controlled by pulses derived from the mains voltage and supplied to tile motor converter by means of a logic circuit, the voltage in the direct-current intermediate circuit being adjusted at the same time through the mains converter to a fixed value and the order for closing a synchronizing switch being given, and that after closing one of the synchronizing switches, the motor is switched to self-regulated operation via the logic circuit.
The method according to the invention has the advantage of rendering possible three-phase drives which combine the advantages of the electric shaft and frequency-converter drive ~torque-conversion), the smaller frequency-con-verter giving a saving of up to 80% of the cost of a full-size converter.
The invention will now be described in greater detail with reference to the accompanying drawing which is a schematic circuit diagram of a circuit for carrying out the method of the invention.
A generator 2 supplying a network, not shown in detail, is driven by a prime-mover 1. Connected to the phases of the network is a frequency-converter synchronous motor 3, to the shaft of which is secured a rotating-field angle-transmitter 4. Motor 3 is connected to -the network by a partial Erequency-converter consisting of a motor current-rectifier (converter) 5, a network current-recti:Eier ~converter) 6, and two iden-tical inductances 7, 8 in the two direct-current in-termediate-circuit branches. With the aid of disconnect switches 9 and 10 which open automatically when the voltage of the generator and motor exceeds the designed voltage of the converter, the partial frequellcy-converter may be cut out after synchronization. When driven by motor 3, the angle-transmitter ~ produces pulses which are passed to a firing pulse selector 11.
- 3a -Pulse selec~Qr devic~ 11 is simultaneously acted upon by pulses taken from the network-voltage through a trigger-circuit 12. Instead of pulses Erom pole-wheel angle transmitter ~, pulse selector 11 may also receive pulses taken from the motor~voltage and formed in a trigger-circuit 13, a possibility indicated by the dotted line running between the network supply and the input-line to the pulse selector 11. In addition to this mechanical and electrical derivation of pulses, pulses may also be obtained magnetically by means of a Hall generator in the air-gap of synchronous motor 3, the pulses being generated in response to the rotating magnetic field of the motor. The three possibilities outlined above are known as the rotatîng-field recognition-system. Pulse selector 11 is connected to feed the thyristors of rectifier 5 either with firing pulses from motor 3 or from generator 2. The firing pulses from motor 3 are formed by angle transmitter ~ or by trigger circuit 13 or by the Hall generator. The firing pulses from generator 2 are formed by trigger circuit 12.
Also provided is a summing circuit 1~ in which the actual frequency fm f motor 3 and the network frequency fG, serving as the rated value, are compared with each other, any frequency deviation ~f acting, through a contact 15a of a s~itch 15, upon a firing circuit 16 for current-converter 6. Switch contact 15a is normally open as are switch contacts 18 and 19 described below but switch contact 15b is normally closed. Pulse selector 11 reverses the condition of these contacts as described below. The firing circuit 16 has another input which is connected through the normally closed contact 15b to the out~ut ~ rated of an intermediate current controller circuit ~not specifically shown) which is, in turn fed by a speed controller ~not shown~. The speed controller and the intermediate current controller ~a?~7~
are standard components of conventional partial converters and are well described in the literature such as "A brushless motor, a new Variable Speed a.c. drive for universal application", AEG-TELEFUNK~N Progess (1973) 3. For that reason they do not form part of the invention. These components are not described in detail.
Finally, a safety-circuit 17 and synchronizing switches 1~J 19 are provided for the relevant direction of rotation.
The method of operation of the arrangement is as follows.
Frequency f of the supply mains is lowered from nominal value by adjusting the generator r.p.m. with prime-mover 1 to the upper limit of converter frequency ~according to maximum nominal load of converter) by lowering of prime-mover speed. The voltage of the generator 2 will be kept constant at maximum design voltage of the partial frequency-converter.
At the same time, the frequency of motor 3 is brought close to the generator frequency with a difference of about 0.25 Hz. The voltage of motor 3 is set to U/f = constant.
The current rectifying synchronous motor 3 is acting as a self-controlled motor~ i.e. the thyristors are fired by pulses detected by rotating field angle transmitter, which are formed by angle-transmitter 4 or out of motor voltage through trigger 13 or by Hall-generators in the motor air-gap. Pulses are also derived through ~rigger-circuit 12, from the mains voltage. Their phase-position in relation to the mains-voltage corresponds approximately to the phase-position of the pulses detected by the rotating field angle transmitter in relation to the motor voltage.
As mentioned above both mains- and motor-fields are rotating with a small frequency difference. Pulse selector 11 is waiting for phase-difference zero between motor- and mains-voltage measured by comparing of both pulse-sequences. If mains- and motor-voltage are in phase pulse-selector 11 will change firepulses for motor current rectifier 5.
7~
Instead of pulses derived from rotating field angle transmitter 4 now pulses derived from mains frequency will fire the thyristors of motor cur-rent rectifier 5. Simultaneously, pulse selector 11 switches the contacts 15a, 15b and orders breaker contact 18 or 19 to closer Opening o-E switch contact 15b switches ofE colltrol-signal ~ rated from the intermediate circuit current control and closing of contact 15a causes, for the purpose of stabili~ing the motor r.p.m., the Erequency-differential signal Qf to be applied to the control input 15a to firing circuit 16, which signal ~f is added to a constant control signal operating on firing circuit 16. The generator frequency, proportional to the mains frequency, may also be obtained by means of a tachometer 20 on the generator shaft.
In the time between ordering breaker 18 or 19 to close till actual breaker closure (switching time constant about 100 - 200 msec) motor 3 is running as an externally controlled current rectifying synchronous motor fired by mains frequency. In this condition, continuous operation under load fluc-tuations is possible without appreciable shift in the phase-positions of the mains and motor-voltage. ~losing of contact 18 or 19 could possibly lead to irregularities in the wave forming of the voltages of the three phases in which case firing unit 12 could detect additional pulses which could cause high currents. By summation of the three mains phase-voltages, a safety-circuit 17 recogni~es whether minor phase-differences between the motor and mains-voltages were present when the switch was closed. This is reported, through a line 21, to pulse-selector 11 which then suppresses the incorrect firing pulses produced by the phase-shift~
In order to avoid high compensating currents through the frequency-converter, the necessary intermediate-circuit inductance is divided into two equal inductances 7, 8 arranged in the two direct-current intermediate-)37~
circuit branchesO In addition to this, and for the same purpose, the firing angle of mains current-rectifier 6 is shifted, as soon as synchronizing s~itch 18~19 is closed, to a value ~ of less than 120o Upon acknowledgement that a synchronizing switch 18 or 19 has been closed, pulse selector ll suppresses the pulses derived from the mains-~oltage and switches the pulses obtained from the rotating-field recognition-system on the motor side to mntor current rectifier 5, i.e. this current-rectifier is changed over from externally-controlled to self-controlled operation. At the same time, the voltage-control of generator 2 is changed over from U = constant to U/f _ constant. As the electric shaft starts up, the U/f - constant control of motor 3 is changed over to a cos. ~ = 1 controlO When the frequenc~_converter reaches its design-voltage, it is switched currentless out of the circuit by isolating switches 9,10.
In three-phase drives for ships it is known to use synchronous motors fed through frequency converters for driving the propellers, whereby the frequency converter must be designed for the entire range of r.p.m. adjust-ments to the motor. Drives of this kind have the disadvantage, however, of being inefficient under partial load and of requiring additional space, additional commutating reactive power and considerable additional expense for the frequency converter.
A high-speed synchronizing method is disclosed in the Japanese patent application 5~-87 521, Abstract E-5~, April 28, 1981, Vol. 5/No. 63, wherein the mains and motor voltages are compared. As long as there are frequency deviations a signal Af is guided to a controller 15 which supplies a higher or lower voltage corresponding to the difference to the synchronous motor via a frequency converter. If the frequency is then equalized, a further signal Sy is then given by the frequency comparison device to a phase comparison device which detects phase differences between the mains and motor voltages and sends a corresponding signal ~ to a correction controller. The signal Sy is simultaneously applied to the controller 15, ensuring that it cannot transmit any further signals changing the speed of the motor. Following the phase equalization, the motor can be switched to the a.c. line.
If the frequency of the prime-mover, for example a Diesel engine, is freely adjustable, it is possible to use an electric shaft which is an arrange-ment in which the prime mover is connected to the propeller shaft by means of i'3'75 a 3-phase a]ternator and a 3-phase motor. Motor speed is controlled by prime mover speed. An electric shaft operates with high efficiency,but it can util-ize only the range of r.p.m. adjustment of the prime mover. In the r.p.m.
range below this, the synchronous motor can start up only asynchronously at a low torque. If the prime mover is a turbine, a high starting torque may be achieved by the use of a separate starting circuit which requires braking of the turbine by means of braking resistances. Here agaill, however, steady operation in the low r.p.m. range is also impossible.
In the work by K. KRANERT "Gasturboantriebe mit elektrischer Welle fuer eisbrechende Tanker", Jahrbuch der Schiffbautechnischen Gesellschaft, Vol. 72, pages 261 to 276, it is proposed to combine the good efficiency of the electric shaft and the good torque behaviour and r.p.m.-adjustment capability of the frequency-converter drive, by the use of a partial frequency-converter. Instead of asynchronous starting of the synchronous motor, this provides for starting with a partial frequency-converter which is a frequency-converter designed for use up to approximately only 40% of nominal voltage and is, therefore, substantially smaller than a complete frequency-converter and it permits torque-shocks and any steady engine r.p.m. If a change-over is made from frequency-converter drive to electric-shaft drive, mains, generator and motor voltages must be synchronized and, thereafter, a synchronizing switch must be closed.
With this known method, successful synchronization is impossible if the motor is loaded or unloaded by a sudden changein torque during the time elapsing between the release of the switching command and the actual closing of the switch (switching time constant). The engine r.p.m. control cannot maintain the momentary r.p.m. because of unavoidable time-constants.
In the e~treme case, the phase positions of the motor and mains voltages run 3'~,5 so far apart that incorrect synchronization may arise when the synchronizing switch is closed. The electric shaft drops out of step, resulting in high compensating currents which may lead to destruction o~ the installation.
It is therefore the purpose of the invention to provide a met~od of tlle type stated in the first paragraph which will ensure the change-over, within an acceptable time, from frequency-converter drive to electric shaft drive - in other words synchronization - even under power impulses (load shocks).
According to a broad aspect of the present invention the method is characterized in that until an approximate in-phase condition of mains and motor voltages is reached, the motor is externally controlled by pulses derived from the mains voltage and supplied to tile motor converter by means of a logic circuit, the voltage in the direct-current intermediate circuit being adjusted at the same time through the mains converter to a fixed value and the order for closing a synchronizing switch being given, and that after closing one of the synchronizing switches, the motor is switched to self-regulated operation via the logic circuit.
The method according to the invention has the advantage of rendering possible three-phase drives which combine the advantages of the electric shaft and frequency-converter drive ~torque-conversion), the smaller frequency-con-verter giving a saving of up to 80% of the cost of a full-size converter.
The invention will now be described in greater detail with reference to the accompanying drawing which is a schematic circuit diagram of a circuit for carrying out the method of the invention.
A generator 2 supplying a network, not shown in detail, is driven by a prime-mover 1. Connected to the phases of the network is a frequency-converter synchronous motor 3, to the shaft of which is secured a rotating-field angle-transmitter 4. Motor 3 is connected to -the network by a partial Erequency-converter consisting of a motor current-rectifier (converter) 5, a network current-recti:Eier ~converter) 6, and two iden-tical inductances 7, 8 in the two direct-current in-termediate-circuit branches. With the aid of disconnect switches 9 and 10 which open automatically when the voltage of the generator and motor exceeds the designed voltage of the converter, the partial frequellcy-converter may be cut out after synchronization. When driven by motor 3, the angle-transmitter ~ produces pulses which are passed to a firing pulse selector 11.
- 3a -Pulse selec~Qr devic~ 11 is simultaneously acted upon by pulses taken from the network-voltage through a trigger-circuit 12. Instead of pulses Erom pole-wheel angle transmitter ~, pulse selector 11 may also receive pulses taken from the motor~voltage and formed in a trigger-circuit 13, a possibility indicated by the dotted line running between the network supply and the input-line to the pulse selector 11. In addition to this mechanical and electrical derivation of pulses, pulses may also be obtained magnetically by means of a Hall generator in the air-gap of synchronous motor 3, the pulses being generated in response to the rotating magnetic field of the motor. The three possibilities outlined above are known as the rotatîng-field recognition-system. Pulse selector 11 is connected to feed the thyristors of rectifier 5 either with firing pulses from motor 3 or from generator 2. The firing pulses from motor 3 are formed by angle transmitter ~ or by trigger circuit 13 or by the Hall generator. The firing pulses from generator 2 are formed by trigger circuit 12.
Also provided is a summing circuit 1~ in which the actual frequency fm f motor 3 and the network frequency fG, serving as the rated value, are compared with each other, any frequency deviation ~f acting, through a contact 15a of a s~itch 15, upon a firing circuit 16 for current-converter 6. Switch contact 15a is normally open as are switch contacts 18 and 19 described below but switch contact 15b is normally closed. Pulse selector 11 reverses the condition of these contacts as described below. The firing circuit 16 has another input which is connected through the normally closed contact 15b to the out~ut ~ rated of an intermediate current controller circuit ~not specifically shown) which is, in turn fed by a speed controller ~not shown~. The speed controller and the intermediate current controller ~a?~7~
are standard components of conventional partial converters and are well described in the literature such as "A brushless motor, a new Variable Speed a.c. drive for universal application", AEG-TELEFUNK~N Progess (1973) 3. For that reason they do not form part of the invention. These components are not described in detail.
Finally, a safety-circuit 17 and synchronizing switches 1~J 19 are provided for the relevant direction of rotation.
The method of operation of the arrangement is as follows.
Frequency f of the supply mains is lowered from nominal value by adjusting the generator r.p.m. with prime-mover 1 to the upper limit of converter frequency ~according to maximum nominal load of converter) by lowering of prime-mover speed. The voltage of the generator 2 will be kept constant at maximum design voltage of the partial frequency-converter.
At the same time, the frequency of motor 3 is brought close to the generator frequency with a difference of about 0.25 Hz. The voltage of motor 3 is set to U/f = constant.
The current rectifying synchronous motor 3 is acting as a self-controlled motor~ i.e. the thyristors are fired by pulses detected by rotating field angle transmitter, which are formed by angle-transmitter 4 or out of motor voltage through trigger 13 or by Hall-generators in the motor air-gap. Pulses are also derived through ~rigger-circuit 12, from the mains voltage. Their phase-position in relation to the mains-voltage corresponds approximately to the phase-position of the pulses detected by the rotating field angle transmitter in relation to the motor voltage.
As mentioned above both mains- and motor-fields are rotating with a small frequency difference. Pulse selector 11 is waiting for phase-difference zero between motor- and mains-voltage measured by comparing of both pulse-sequences. If mains- and motor-voltage are in phase pulse-selector 11 will change firepulses for motor current rectifier 5.
7~
Instead of pulses derived from rotating field angle transmitter 4 now pulses derived from mains frequency will fire the thyristors of motor cur-rent rectifier 5. Simultaneously, pulse selector 11 switches the contacts 15a, 15b and orders breaker contact 18 or 19 to closer Opening o-E switch contact 15b switches ofE colltrol-signal ~ rated from the intermediate circuit current control and closing of contact 15a causes, for the purpose of stabili~ing the motor r.p.m., the Erequency-differential signal Qf to be applied to the control input 15a to firing circuit 16, which signal ~f is added to a constant control signal operating on firing circuit 16. The generator frequency, proportional to the mains frequency, may also be obtained by means of a tachometer 20 on the generator shaft.
In the time between ordering breaker 18 or 19 to close till actual breaker closure (switching time constant about 100 - 200 msec) motor 3 is running as an externally controlled current rectifying synchronous motor fired by mains frequency. In this condition, continuous operation under load fluc-tuations is possible without appreciable shift in the phase-positions of the mains and motor-voltage. ~losing of contact 18 or 19 could possibly lead to irregularities in the wave forming of the voltages of the three phases in which case firing unit 12 could detect additional pulses which could cause high currents. By summation of the three mains phase-voltages, a safety-circuit 17 recogni~es whether minor phase-differences between the motor and mains-voltages were present when the switch was closed. This is reported, through a line 21, to pulse-selector 11 which then suppresses the incorrect firing pulses produced by the phase-shift~
In order to avoid high compensating currents through the frequency-converter, the necessary intermediate-circuit inductance is divided into two equal inductances 7, 8 arranged in the two direct-current intermediate-)37~
circuit branchesO In addition to this, and for the same purpose, the firing angle of mains current-rectifier 6 is shifted, as soon as synchronizing s~itch 18~19 is closed, to a value ~ of less than 120o Upon acknowledgement that a synchronizing switch 18 or 19 has been closed, pulse selector ll suppresses the pulses derived from the mains-~oltage and switches the pulses obtained from the rotating-field recognition-system on the motor side to mntor current rectifier 5, i.e. this current-rectifier is changed over from externally-controlled to self-controlled operation. At the same time, the voltage-control of generator 2 is changed over from U = constant to U/f _ constant. As the electric shaft starts up, the U/f - constant control of motor 3 is changed over to a cos. ~ = 1 controlO When the frequenc~_converter reaches its design-voltage, it is switched currentless out of the circuit by isolating switches 9,10.
Claims (4)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method for synchronizing a frequency converter-synchronous motor having a three-phase mains supply through a partial converter including a mains converter and motor converter connected together by a direct-current intermediate circuit and in which devices are used to detect frequency and phase positions of the motor and mains, characterized in that until an approx-imate in-phase condition of mains and motor voltages is reached, the motor is externally controlled by pulses, derived from the mains voltage and supplied to the motor converter by means of a logic circuit, the voltage in the direct-current intermediate circuit being adjusted at the same time through the mains converter to a fixed value and the order for closing a synchronizing switch being given, and that after closing one of the synchronizing switches, the motor is switched to self-regulated operation via the logic circuit.
2. A method according to claim 1, characterized in that for stabilizing the externally controlled operation of the frequency converter-synchronous motor a difference signal (.DELTA.f) formed from the motor and mains frequency is switched additionally to a control unit for the mains converter.
3. A method according to claim 1, characterized in that minor phase deviations between the motor and mains voltage are recognized by summation of the three mains phase voltages in a safety device and pulses from the logic circuit are blocked by said safety device.
4. A method according to claim 1, characterized in that for limiting compensating currents an inductance arranged in the direct-current intermediate circuit is divided into two branches and the firing angle (.alpha.) of the mains converter is adjusted, after synchronization, to a value of more than 120°.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19813133311 DE3133311C2 (en) | 1981-08-22 | 1981-08-22 | Method for synchronizing a converter synchronous motor with a feeding network |
| DEP3133311.7 | 1981-08-22 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1180375A true CA1180375A (en) | 1985-01-02 |
Family
ID=6139920
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000409919A Expired CA1180375A (en) | 1981-08-22 | 1982-08-23 | Method for synchronizing a current-rectifying synchronous motor with a mains-supply |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA1180375A (en) |
| DE (1) | DE3133311C2 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3310506A1 (en) * | 1983-03-23 | 1984-09-27 | Licentia Patent-Verwaltungs-Gmbh, 6000 Frankfurt | CONTINUOUS ON-LINE NETWORK SUPPLY FROM THE VEHICLE NETWORK FOR THREE-PHASE VESSEL DRIVES WITH VARIABLE FREQUENCY AND SUB-CONVERTER |
| DE102008018923A1 (en) * | 2008-04-15 | 2009-10-22 | Siemens Aktiengesellschaft | Constant speed drive |
| WO2016143481A1 (en) * | 2015-03-10 | 2016-09-15 | 株式会社明電舎 | Synchronization control device for power converter |
-
1981
- 1981-08-22 DE DE19813133311 patent/DE3133311C2/en not_active Expired
-
1982
- 1982-08-23 CA CA000409919A patent/CA1180375A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| DE3133311A1 (en) | 1983-03-10 |
| DE3133311C2 (en) | 1985-03-07 |
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