This application claims the benefit of the priority filing date in Brazilian patent no. PI 1103937-0 filed with the Brazilian Patent Office on Sep. 5, 2011. The earliest priority date claimed is Sep. 5, 2011.
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Portions of the disclosure of this patent document contain material that is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure as it appears in the Patent and Trademark Office file or records, but otherwise reserves all copyright rights whatsoever.
The present description relates to an automatic reversible synchronizing switching circuit in the field of electrical devices for engine driving and feeding. It was planned, designed and developed with the purpose of making its functions more versatile and optimized by working as an additional control circuit intended to be used for driving permanent magnet synchronous engines by means of a frequency inverter, and incorporated into the inverter or externally connected to the inverter (electronics/drive-dedicated).
Thus, said automatic reversible synchronizing switching circuit allows the engine driven by the inverter to start while being fed directly by the network, in synchronous rotation, and vice-versa. The engine is fed again by the inverter for use in other rotations, also allowing the transference to the network to be automatic or not, whatever the case may be.
The condition of operating directly in the network on synchronous rotation mode provides the engine maximum output, avoiding losses when the frequency inverter is used. Thus, the function of said circuit allows the engine to always be used, mainly when the engine works only at fixed rotation, equal or close to its synchronous rotation, but also in applications in which the engine works part of the time at fixed rotation, equal or close to its synchronous rotation, and other part of the time, at different rotations, adjusted by the inverter.
As is known mainly by those skilled in the art and concerning the state-of-the-art, a larger permanent magnet synchronous engine may only be put into movement and accelerated up to the desired rotation by a keyed device, in this case, the frequency inverter, or similar device.
The change from a close-to-synchronous routine to a synchronous one itself, as it occurs when an induction engine is replaced with a permanent magnet engine, fed by the network, may obviously affect the equipment.
When the fans are big, for example, the absorbed power may spread to an undesirable path, so it is up to the user to:
(a) keep the exact and desirable permanent magnet engine rotation by using the inverter;
(b) make any changes to the engine's replacement for it to rotate in synchronous rotation with the power absorbed previously, considering the power saving it provides.
However, if this desired rotation is fixed and close to the engine's synchronous rotation, as it is like in all replacements of induction engines with permanent magnet synchronous engines, the permanent magnet synchronous engine continues to be fed by its high output, because it operates in the inverter, and not in the network.
To minimize such inconveniences, there are converters that allow transference of feeding from the engine to the network, but only for maintenance purposes. This is done in such a way that, in replacements of induction engines with permanent magnets engines, feeding by the inverter is not automatically eliminated, resulting in these replacements not being effectively made. The permanent magnet engine continues operating by being fed by the inverter, even when close to its synchronous rotation, causing decreased efficiency of the permanent magnet engine.
The present description relates to an automatic reversible synchronizing switching circuit in the field of electrical devices for engine driving and feeding. Once automatic engine-network synchronization is selected for a permanent magnet synchronous polyphase engine driven by a frequency inverter with “start” control, the present automatic reversible synchronizing switching circuit would supervise the starting period by means of a setting button for a pre-established frequency ramp versus time. When reaching the engine's synchronous rotation, the circuit transfers its feeding directly to the network. At the first moment, the circuit separates the engine from the inverter, and thereafter, switches the engine to the network. Finally, if the option “automatic inverter stop” is selected, the circuit turns the variator itself off.
If “automatic engine-network synchronization” is not selected, said circuit may perform this transference at any moment, at the operator's or at the general control system's request, by using the control: “synchronize and switch: engine to network”.
Said automatic reversible synchronizing switching circuit may also perform the inverse function, i.e., transferring the engine feeding from the network to the inverter, anytime the operator or the general system sets this function by using the control: “synchronize and switch: inverter to engine”.
In this case, the circuit automatically turns the inverter on, switching the inverter to the network frequency and transferring feeding from the (moving) engine to the converter. First, the circuit disconnects the inverter from the network and immediately thereafter, connects the network to the inverter.
If the process requires deceleration, the circuit provides engine deceleration with a setting button for another pre-established frequency ramp versus time, up to synchronous rotation.
To perform these transferences at the most appropriate moment, an automatic reversible synchronizing switching circuit is provided with a synchronization module. The module checks the network and converter voltages for value, angle and phase, frequency and phase sequence, in order to reduce abnormal currents that may damage any part of the system.
Said circuit may also supervise the engine by means of a thermal protection and/or circuit breaker, or also by means of signals received from sensors (vibration, rotation and temperature), and installed in the engine.
According to said diagram and consonant to the description herein provided, the present application for a patent of invention relates to an automatic reversible synchronizing switching circuit, in the field of electrical devices for engines driving and feeding, comprising:
Once the automatic engine-network synchronization is selected for a permanent magnet synchronous polyphase engine driven by a frequency inverter with “start” control, the present automatic reversible synchronizing switching circuit would supervise the starting period by means of a setting button for a pre-established frequency ramp versus time. When reaching the engine's synchronous rotation, the circuit transfers its feeding directly to the network. At the first moment, the circuit separates the engine from the inverter, and thereafter, switches the engine to the network. Finally, if the option “automatic inverter stop” is selected, the circuit turns the variator itself off.
If “automatic engine-network synchronization” is not selected, said circuit may perform this transference at any moment, at the operator's or at the general control system's request, by using the control: “synchronize and switch: engine to network”.
Said automatic reversible synchronizing switching circuit may also perform the inverse function, i.e., transferring the engine feeding from the network to the inverter, anytime the operator or the general system sets this function by using the control: “synchronize and switch: inverter to engine”.
In this case, the circuit automatically turns the inverter on, switching the inverter to the network frequency and transferring feeding from the (moving) engine to the converter. First, the circuit disconnects the inverter from the network and immediately thereafter, connects the network to the inverter.
If the process also requires deceleration, the circuit provides engine deceleration with a setting button for another pre-established frequency ramp versus time, up to synchronous rotation.
To perform these transferences at the most appropriate moment, an automatic reversible synchronizing switching circuit is provided with a synchronization module. The module checks the network and converter voltages for value, angle and phase, frequency and phase sequence, in order to reduce abnormal currents that may damage any part of the system.
It is important to emphasize that the automatic reversible synchronizing switching circuit does not require an encoder.
Said circuit may also supervise the engine by means of a thermal protection and/or circuit breaker, or also by means of signals received from sensors (vibration, rotation and temperature), and installed in the engine.
Related thereto, and also concerning conventional devices, the present automatic reversible synchronizing switching circuit is different and outstanding because the circuit adds the following advantages and benefits:
Thus, every solution and advantage identified above directly influence lower industrialization costs and is reflected in the final commercialization price, among other overruling aspects, thereby benefiting the whole corresponding manufacturing sector.
It is important to emphasize that the frequency inverter, along with said automatic reversible synchronizing switching circuit may be incorporated into the engine itself, in the same way as converters. In addition, said circuit is also very useful in water pumping systems with multiple pumps (such as public sanitation services), in which the system may decide which pump takes on its regulating function, at adjustable speeds, while other pumps work at synchronous speeds. Full output permanent magnet synchronous engines also offer the possibility of permanent magnet engines working together in other required applications.
Despite the detailing of the present invention, it is important to emphasize that it does not limit its application to the aspects and features herein exemplified, once other modalities may be practiced or performed in a variety of ways, and it shall be understood that the terminology herein used was provided with the purpose of descriptions and not limitation.
Number | Date | Country | Kind |
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PI 1103937-0 | Sep 2011 | BR | national |