CA2486767A1 - Three phase transformer with dual toroidal flux return path - Google Patents
Three phase transformer with dual toroidal flux return path Download PDFInfo
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- CA2486767A1 CA2486767A1 CA 2486767 CA2486767A CA2486767A1 CA 2486767 A1 CA2486767 A1 CA 2486767A1 CA 2486767 CA2486767 CA 2486767 CA 2486767 A CA2486767 A CA 2486767A CA 2486767 A1 CA2486767 A1 CA 2486767A1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F30/00—Fixed transformers not covered by group H01F19/00
- H01F30/06—Fixed transformers not covered by group H01F19/00 characterised by the structure
- H01F30/12—Two-phase, three-phase or polyphase transformers
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F27/00—Details of transformers or inductances, in general
- H01F27/24—Magnetic cores
- H01F27/245—Magnetic cores made from sheets, e.g. grain-oriented
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Coils Of Transformers For General Uses (AREA)
Abstract
The invention is a dry type Three-Phase Transformer with toroidal yoke. It develops high power density (ratio of power to active volume) in the magnitude of 3.0 times the existing three phase technology. The invention provides more power density and less stray magnetic field by use of a different shape and design.
Particularly, it is a cylindrical shape that occupies less space. The invention is used for increasing and more efficiently delivering power to electrical equipment while being lighter and more compact. The main component is a toroidal core, which is wound with continuous tape of grain oriented silicon steel (GOSS) with no gaps and all the grains orientated in a preferred direction, being used as a yoke in the structure of the transformer.
Particularly, it is a cylindrical shape that occupies less space. The invention is used for increasing and more efficiently delivering power to electrical equipment while being lighter and more compact. The main component is a toroidal core, which is wound with continuous tape of grain oriented silicon steel (GOSS) with no gaps and all the grains orientated in a preferred direction, being used as a yoke in the structure of the transformer.
Description
PATENT APPLICATION
NAME OF INVENTION:
THREE PHASE TRANSFORMER WITH
DUAL TOROIDAL FLUX RETURN PATH
TITLE: THREE-PHASE TRANSFORMER WITH
DUAL TOROIDAL FLUX RETURN PATH
Technical Field ofthe Inver~iOn The invention is related to the field of three-phase power transformers for which a gapless tape-wound toroidal core provides the inter-phase flux return path, allowing performance improvements compared to existing technology. The invention increases power density with reduced materials requirements.
F~dsfing Three Phase Technology The existing construction of three-phase power transformers was developed over one hundred years ago. Although raw materials such as steel cores and winding conductor characteristics have improved since, there have been few, if any, enhancements to design and construction.
The transformer construction technique is dependent on the selected core configuration, which is a primary design consideration and which also determines energy losses.
The most significant energy loss component is in the form of 12R, or 'winding losses'. The roof of the problem is the inability to utilize the core efficiently. This inefficiency is a significant contributing factor to the winding resistance 'R', which contributes to the inefficiency. Such losses are large enough to become a power design consideration for improving efFciency.
This is because existing three-phase technology makes poor utilization of the grain structure and cannot take advantage of the high quality electrical steels available today, Power tosses are therefore seen in the form of heat and mechanical noise.
The construction and geometry of existing three phase transformers was developed for ease of manufacture, and not for performance.
Figure 1a shows three-phase EI transformer construction, named for the utilization of stamped E-shaped and I-shaped grain-oriented electrical steel laminations, which are alternately stacked and assembled around pre-wound bobbins. The laminations are annealed to relieve the stresses of the stamping machine, but stresses can be re-introduced into the material during the assembly stage. Lamination stamping equipment is costly but transformer manufacturing costs are kept low as lamination stamping is a high-volume automated process, and multi-winding bobbin capability is common.
The EI transformer makes poor use of the core because a significant portion of magnetic grains are not aligned with the preferred flux direction, and because gaps exist at every layer. This increases core watt losses and requires a lower flux density, increasing cost, materials consumption and weight. This results in reduced efficiency and wider regulation. In addition, it is necessary to vacuum varnish the EI
assembly to control the noise associated with core losses.
Another common core geometry, similar to the EI, makes use of a distributed gap core. Strips of electrical steel are annealed and then assembled individually by layer around wound bobbins. Unlike the Els described above, the grains are oriented in the preferred direction.
However, inherent in the construction are air gaps. Every layer contains an air gap which yields negative effects, such as mechanical noise from lamination chatter, high magnetic emissions, and most significantly, increased exciting currents. It is common that operating flux densities be lowered to compensate for exciting currents, which increase materials consumption, weight, and costs. These increases can result in reduced efficiency and regulation.
EI and Distributed Gap construction have performance issues which are accepted to for ease All transformers generate a flux circuit, which includes a return flux path. Both of the two systems above use a similar style of flux return system. The total flux generated by the current-carrying conductor flows through the limbs (the sections of the transformer lamination stack around which the windings are wound). This flux also passes through the yoke (the stack of steel laminations of the transformer that link the limbs together to close the magnetic loop). In the case of existing technology, the yokes are straight-shape and in the invented design the yoke is circular-shape (toroidal yokes). The cross-section of the yoke is, therefore, required to be the same as the cross-section of the limbs to accommodate the flux.
Invented Three-Phase Technology Figure 1b shows the invented three-phase transformer with dual toroidal flux return path. It is constructed from three limbs that are stacked laminations of grain-oriented silicon steel and two tape-wound toroidal yokes. The orientation of the magnetic grains in the yokes is aligned with the magnetic flux lines. Each limb has both primary and secondary windings of one phase wound around it. The three wound limbs are then positioned, equally spaced, around the surface of one of the toroidal yokes, with the other toroidal yoke placed on the top. Therefore, the three wound limbs are in fact sandwiched between the two toroidal yokes.
The number of turns and wire gauge of the primary and the secondary windings, cross-sectional area of the limbs and material of the tape wound toroids and stacked lamination of the limbs are all calculated through a developed design procedure.
The basis of the design formula, which defines the relationships of voltages to magnetic flux, is Faraday's law, which holds:
e(t) = N. d~(t)/dt Equation 1 Where "e(t)" is instantaneous voltage at the terminal of the winding, N is the number of turns and ~(t) is instantaneous magnetic flux.
For a sinusoidal voltage E, equation1 is written in phasor form:
E = jwNd~, Equation 2 Where j~ is the phasor operator for d/dt. The equation 2 can be written in the form of the magnitude and the angle as below;
~ E~ = wN~, and LE = c~Nc~G90 Equation 3 where w is the radian frequency Now flux;
~ = B.A Equation 4 Where B is flux density and A is cross-sectional area of the limb.
Substituting Equation 4 in Equation 3;
~ E~ = N w B A = 2~ f N B A Equation 5 The use of tape-wound toroids as yokes provides two separate flux return paths per phase to close its magnetic circuit across the yoke section.
Therefore, the cross-section of the yoke needs to be only half that of the limb, and half that of existing three phase technology. This phenomenon is illustrated in Figures 2a and 2b which show an electric circuit analog of the magnetic circuit of the invented design as well as existing technology, showing a comparison and analysis. In the figures, the battery voltage represents the winding magneto-motive force (mmf or Ampere-Tum), resistance R represents the reluctance of the air-gap between the limb and the yoke, and the current I represents the generated magnetic flux.
_4-Both the current and the voltage are function of time since the excitation source is a sinusoidal function.
The general shape of the current waveform in a three-phase application is shown in Figure 3. This is a balanced three-phase current waveform. As presented, the sum of the instantaneous currents of the three phases is zero. The current in each phase goes through an excursion of zero to positive maximum back to zero and negative maximum and again back to zero. In order to demonstrate the difference between the two existing technologies and the invented technology, an instant of time (wt = 90°) where one phase (phase1 ) is at its peak current and the other two (phases B and C) at half that current but running in an opposite direction is chosen as shown in Figure 3. This time represents the instant of time that maximum flux passes through one section of the yoke in both the existing technology and the invented technology.
To investigate the distribution of current (flux) around the circuit, KirchofPs Current Law (KCL) is applied to both the existing technology equivalent circuit and the invented technology equivalent circuit, shown in Figures 2a and 2b. Kirchoffs Current Law holds that the sum of the currents at any instant of time entering an electrical node must be equal to the sum of the currents exiting the same node. The currents are time variant, so they are all considered as function of time (t).
Existing Technology, Figure 2a;
KCL for:
Node A: i~~(t) = iy~(t) Equation (6) Node B: i~2(t) + iY2(t)= iY~ (t) Equation (7) Node C: iy2(t) = i~3(t) Equation (8) Where I~,(t), i,~(t) and i~3(t) represents the current in Limbs 1,2 and 3. And iY~(t) and iY2(t ) are currents in sections of the yokes between limbs1-2 and limbs 2-3 Invented Technology, figure 2b;
KCL for:
Node A: i~,(t) = iY,(t) + iYZ(t) Equation (9) Node B: iY~(t) = i~z(t) Equation (10) _ 5' Node C: iY2(t) = i~3(t) Equation (11) Where I~~ (t), i,~(t) and i~3(t) represents the current in Limbs 1,2 and 3.
And iY~(t) and iY2(t ) are currents in sections of the yokes between limbs1-2 and limbs 1-3.
Comparing the distribution of current at Node A for both models, it is clear from Equation (6), in the case of the existing technology, that the current in limb 1 is equal to the current in that section of the yoke that links limb1 to limb 2. Given that current represents flux in the equations, it is recognized that the total flux in limb 1 must pass through the yoke. Therefore, the cross-section of the yoke must be equal to the cross-section of the limb. .
In the case of the invented technology, Equation (9) shows that the current in limb1 is divided into two equal components (Equal component is derived from Equation (10) and (11 ) since i~2 and i~3 are equal at that instant of time.).In this case, the flux in the limb is diverted to two paths when flowing through the yoke. These dual paths are equal, requiring the yoke to be half the cross-sectional area of the limb..
Heat Transfer Comparison The ability to dissipate and remove heat from a transformer and maintain the operating temperature within the insulation class rating is directly related to important performance characteristics such as power rating, temperature rise, power density, efficiency, size, weight, and ultimately cost. An inefficient thermal circuit will result in large, oversized, inefficient transformers.
The cooling in the existing transformers is generally done by the natural air circulation through the transformer or by a forced-air method. Due to the rectilinear shape of existing transformers, there is no one position in the transformer that a fan can be installed to remove heat uniformly from all phases. However, in the invented technology due to the cylindrical shape of the transformer and the presence of an air tunnel in the center of the construction, as shown in Figure 4, heat can be removed uniformly by the use of fans installed at both ends of the transformer. Figure 5 shows a 30KVA prototype of the invented three-phase with fans installed at both ends. Fans are installed so that the cold air (at ambient temperature) is pushed inside the air-tunnel from both ends and forcing the heat away from the transformer.
The invention is a three-phase transformer with dual toroidal flux return, which is capable of developing higher power density (ratio of power to volume) in the magnitude of 3.0 times the existing three-phase technology.
The technical explanation is as follows:
1) The yokes are constructed of tape-wound toroid, which join the limbs together, and makes the transformer cylindrical in shape. The cylindrical shape of the transformer allows increased power density of the form of (power / volume) to be achieved as compared to existing (rectilinear shape) transformers.
NAME OF INVENTION:
THREE PHASE TRANSFORMER WITH
DUAL TOROIDAL FLUX RETURN PATH
TITLE: THREE-PHASE TRANSFORMER WITH
DUAL TOROIDAL FLUX RETURN PATH
Technical Field ofthe Inver~iOn The invention is related to the field of three-phase power transformers for which a gapless tape-wound toroidal core provides the inter-phase flux return path, allowing performance improvements compared to existing technology. The invention increases power density with reduced materials requirements.
F~dsfing Three Phase Technology The existing construction of three-phase power transformers was developed over one hundred years ago. Although raw materials such as steel cores and winding conductor characteristics have improved since, there have been few, if any, enhancements to design and construction.
The transformer construction technique is dependent on the selected core configuration, which is a primary design consideration and which also determines energy losses.
The most significant energy loss component is in the form of 12R, or 'winding losses'. The roof of the problem is the inability to utilize the core efficiently. This inefficiency is a significant contributing factor to the winding resistance 'R', which contributes to the inefficiency. Such losses are large enough to become a power design consideration for improving efFciency.
This is because existing three-phase technology makes poor utilization of the grain structure and cannot take advantage of the high quality electrical steels available today, Power tosses are therefore seen in the form of heat and mechanical noise.
The construction and geometry of existing three phase transformers was developed for ease of manufacture, and not for performance.
Figure 1a shows three-phase EI transformer construction, named for the utilization of stamped E-shaped and I-shaped grain-oriented electrical steel laminations, which are alternately stacked and assembled around pre-wound bobbins. The laminations are annealed to relieve the stresses of the stamping machine, but stresses can be re-introduced into the material during the assembly stage. Lamination stamping equipment is costly but transformer manufacturing costs are kept low as lamination stamping is a high-volume automated process, and multi-winding bobbin capability is common.
The EI transformer makes poor use of the core because a significant portion of magnetic grains are not aligned with the preferred flux direction, and because gaps exist at every layer. This increases core watt losses and requires a lower flux density, increasing cost, materials consumption and weight. This results in reduced efficiency and wider regulation. In addition, it is necessary to vacuum varnish the EI
assembly to control the noise associated with core losses.
Another common core geometry, similar to the EI, makes use of a distributed gap core. Strips of electrical steel are annealed and then assembled individually by layer around wound bobbins. Unlike the Els described above, the grains are oriented in the preferred direction.
However, inherent in the construction are air gaps. Every layer contains an air gap which yields negative effects, such as mechanical noise from lamination chatter, high magnetic emissions, and most significantly, increased exciting currents. It is common that operating flux densities be lowered to compensate for exciting currents, which increase materials consumption, weight, and costs. These increases can result in reduced efficiency and regulation.
EI and Distributed Gap construction have performance issues which are accepted to for ease All transformers generate a flux circuit, which includes a return flux path. Both of the two systems above use a similar style of flux return system. The total flux generated by the current-carrying conductor flows through the limbs (the sections of the transformer lamination stack around which the windings are wound). This flux also passes through the yoke (the stack of steel laminations of the transformer that link the limbs together to close the magnetic loop). In the case of existing technology, the yokes are straight-shape and in the invented design the yoke is circular-shape (toroidal yokes). The cross-section of the yoke is, therefore, required to be the same as the cross-section of the limbs to accommodate the flux.
Invented Three-Phase Technology Figure 1b shows the invented three-phase transformer with dual toroidal flux return path. It is constructed from three limbs that are stacked laminations of grain-oriented silicon steel and two tape-wound toroidal yokes. The orientation of the magnetic grains in the yokes is aligned with the magnetic flux lines. Each limb has both primary and secondary windings of one phase wound around it. The three wound limbs are then positioned, equally spaced, around the surface of one of the toroidal yokes, with the other toroidal yoke placed on the top. Therefore, the three wound limbs are in fact sandwiched between the two toroidal yokes.
The number of turns and wire gauge of the primary and the secondary windings, cross-sectional area of the limbs and material of the tape wound toroids and stacked lamination of the limbs are all calculated through a developed design procedure.
The basis of the design formula, which defines the relationships of voltages to magnetic flux, is Faraday's law, which holds:
e(t) = N. d~(t)/dt Equation 1 Where "e(t)" is instantaneous voltage at the terminal of the winding, N is the number of turns and ~(t) is instantaneous magnetic flux.
For a sinusoidal voltage E, equation1 is written in phasor form:
E = jwNd~, Equation 2 Where j~ is the phasor operator for d/dt. The equation 2 can be written in the form of the magnitude and the angle as below;
~ E~ = wN~, and LE = c~Nc~G90 Equation 3 where w is the radian frequency Now flux;
~ = B.A Equation 4 Where B is flux density and A is cross-sectional area of the limb.
Substituting Equation 4 in Equation 3;
~ E~ = N w B A = 2~ f N B A Equation 5 The use of tape-wound toroids as yokes provides two separate flux return paths per phase to close its magnetic circuit across the yoke section.
Therefore, the cross-section of the yoke needs to be only half that of the limb, and half that of existing three phase technology. This phenomenon is illustrated in Figures 2a and 2b which show an electric circuit analog of the magnetic circuit of the invented design as well as existing technology, showing a comparison and analysis. In the figures, the battery voltage represents the winding magneto-motive force (mmf or Ampere-Tum), resistance R represents the reluctance of the air-gap between the limb and the yoke, and the current I represents the generated magnetic flux.
_4-Both the current and the voltage are function of time since the excitation source is a sinusoidal function.
The general shape of the current waveform in a three-phase application is shown in Figure 3. This is a balanced three-phase current waveform. As presented, the sum of the instantaneous currents of the three phases is zero. The current in each phase goes through an excursion of zero to positive maximum back to zero and negative maximum and again back to zero. In order to demonstrate the difference between the two existing technologies and the invented technology, an instant of time (wt = 90°) where one phase (phase1 ) is at its peak current and the other two (phases B and C) at half that current but running in an opposite direction is chosen as shown in Figure 3. This time represents the instant of time that maximum flux passes through one section of the yoke in both the existing technology and the invented technology.
To investigate the distribution of current (flux) around the circuit, KirchofPs Current Law (KCL) is applied to both the existing technology equivalent circuit and the invented technology equivalent circuit, shown in Figures 2a and 2b. Kirchoffs Current Law holds that the sum of the currents at any instant of time entering an electrical node must be equal to the sum of the currents exiting the same node. The currents are time variant, so they are all considered as function of time (t).
Existing Technology, Figure 2a;
KCL for:
Node A: i~~(t) = iy~(t) Equation (6) Node B: i~2(t) + iY2(t)= iY~ (t) Equation (7) Node C: iy2(t) = i~3(t) Equation (8) Where I~,(t), i,~(t) and i~3(t) represents the current in Limbs 1,2 and 3. And iY~(t) and iY2(t ) are currents in sections of the yokes between limbs1-2 and limbs 2-3 Invented Technology, figure 2b;
KCL for:
Node A: i~,(t) = iY,(t) + iYZ(t) Equation (9) Node B: iY~(t) = i~z(t) Equation (10) _ 5' Node C: iY2(t) = i~3(t) Equation (11) Where I~~ (t), i,~(t) and i~3(t) represents the current in Limbs 1,2 and 3.
And iY~(t) and iY2(t ) are currents in sections of the yokes between limbs1-2 and limbs 1-3.
Comparing the distribution of current at Node A for both models, it is clear from Equation (6), in the case of the existing technology, that the current in limb 1 is equal to the current in that section of the yoke that links limb1 to limb 2. Given that current represents flux in the equations, it is recognized that the total flux in limb 1 must pass through the yoke. Therefore, the cross-section of the yoke must be equal to the cross-section of the limb. .
In the case of the invented technology, Equation (9) shows that the current in limb1 is divided into two equal components (Equal component is derived from Equation (10) and (11 ) since i~2 and i~3 are equal at that instant of time.).In this case, the flux in the limb is diverted to two paths when flowing through the yoke. These dual paths are equal, requiring the yoke to be half the cross-sectional area of the limb..
Heat Transfer Comparison The ability to dissipate and remove heat from a transformer and maintain the operating temperature within the insulation class rating is directly related to important performance characteristics such as power rating, temperature rise, power density, efficiency, size, weight, and ultimately cost. An inefficient thermal circuit will result in large, oversized, inefficient transformers.
The cooling in the existing transformers is generally done by the natural air circulation through the transformer or by a forced-air method. Due to the rectilinear shape of existing transformers, there is no one position in the transformer that a fan can be installed to remove heat uniformly from all phases. However, in the invented technology due to the cylindrical shape of the transformer and the presence of an air tunnel in the center of the construction, as shown in Figure 4, heat can be removed uniformly by the use of fans installed at both ends of the transformer. Figure 5 shows a 30KVA prototype of the invented three-phase with fans installed at both ends. Fans are installed so that the cold air (at ambient temperature) is pushed inside the air-tunnel from both ends and forcing the heat away from the transformer.
The invention is a three-phase transformer with dual toroidal flux return, which is capable of developing higher power density (ratio of power to volume) in the magnitude of 3.0 times the existing three-phase technology.
The technical explanation is as follows:
1) The yokes are constructed of tape-wound toroid, which join the limbs together, and makes the transformer cylindrical in shape. The cylindrical shape of the transformer allows increased power density of the form of (power / volume) to be achieved as compared to existing (rectilinear shape) transformers.
2) The circular shape of the toroidal yokes allow the generated flux in each limb to offer two discreet paths along the yoke to close its respective magnetic loop.
This phenomenon, as explained in Section "Invented Three-Phase Technology", translates into a lighter weight transformer as compared to the existing technology. This is because the cross-section of the yoke can be half that of the limb, therefore, lighter in weight compared to the existing technology where the yoke and the limbs have the same cross-section.
This phenomenon, as explained in Section "Invented Three-Phase Technology", translates into a lighter weight transformer as compared to the existing technology. This is because the cross-section of the yoke can be half that of the limb, therefore, lighter in weight compared to the existing technology where the yoke and the limbs have the same cross-section.
3) The invented geometry creates a natural tunnel, which can be utilized effectively to increase airflow across the windings. In the invention, heat is removed uniformly from all three phases easily, efficiently, and simultaneously. Two fans each positioned at an end of the transformer supply airflow. The fans are located such that ambient air is blown inside the tunnel in the center, and simultaneously cools the surface of all three phases at the same rate. This level of cooling cannot be achieved with the existing technology, as there is no one physical position in the transformer where the fan can be placed to remove heat uniformly from the three phases. Further, as they draw cool ambient air from outside of the transformer and direct it to the transformer's central tunnel, the fans are not exposed to hot air. This lengthens the working life time of the fans. Note:
Use of fans is optional, and specific to the application.
Use of fans is optional, and specific to the application.
4) A 30KVA prototype based on the invented technology was built, as shown in Figure 5 and a full load test was conducted. A similar full load test was performed on a 30KVA transformer with the existing technology. Figure 6 displays the performance comparison between the two transformers. Comparing the key features between the two technologies, the following conclusions are observed:
- Steel weight: The invented technology uses 55.6 Kg of steel, where as the existing technology uses 65.9 Kg. This shows approximately 16% less steel is used by the invented technology.
- Overall active weight: This is the weight of copper and steel combined. The invented technology weight is 78.3 Kg and the existing technology weight is _ -~- -88.2 Kg. This shows that the invented technology is lighter by approximately 11 %.
Volume of space taken, including the frame construction: The invented technology occupies 82500 cm3 and the existing technology takes 51183 cm3 of space. Therefore, the invented model takes approximately 38% less space than the existing model.
Power densities: Two forms of power densities are compared. 1 ) Ratio of power to volume (VA I Volume); the invented technology has 0.59 ratio and the existing technology has 0.36 ratio. The invented model has 64%
better power density. 2) Ratio of power to weight (VA / Kg); the invented technology has 353 ratio and the existing technology has 275 ratio.
Therefore, the invented model has 28% more power density.
$ ._ A detailed description of the preferred embodiment is provided below with reference to the following:
Figures 1a and 1b show the pictorial drawings of the invented three-phase transformer and an existing EI three-phase transformer. The invented three-phase consists of three limbs, around which windings are wound, two tape-wound toroidal yokes and two fans. Each wound limb represents one phase of the three-phase system. The three wound limbs are positioned, equally spaced, around the surface of the toroidal yokes.
Two fans that blow air inside the tunnel are placed at both ends of the assembly.
In the existing E-I three-phase transformer, Figure 1a, the limbs are referred to that section of the stacked EI laminations around which the windings are wound, and yokes are referred to in the sections that join the limbs together.
Figure 2 shows the electric circuit analog of the magnetic circuit of an existing three-phase transformer, and the invented three-phase transformer. The battery voltage represents the winding magneto motive force (mmf or Ampere-Turn). Resistance R represents the reluctance of the air-gap between the limb and the yoke and the current I represents the generated magnetic flux.
Figure 3 shows a balanced three-phase excitation waveform. The graph demonstrates a three-phase excitation for a three-phase transformer, showing the level of the excitation at various moments in each cycle and also indicating that the sum of instantaneous voltages is equal to zero.
Figure 4 shows the outline of the air-tunnel and the forced-air flow in the invented three-phase transformer with fans placed at both ends of the transformer.
Figure 5 shows the picture of the 30KVA prototype of the invented three-phase transformer, which includes the transformer and the casing assembly.
Figure 6 compares the performance of the 30kVA invented three-phase prototype transformer with an existing off-the-shelf three-phase transformer.
Numbering of the described elements of the drawings 1 Limb
- Steel weight: The invented technology uses 55.6 Kg of steel, where as the existing technology uses 65.9 Kg. This shows approximately 16% less steel is used by the invented technology.
- Overall active weight: This is the weight of copper and steel combined. The invented technology weight is 78.3 Kg and the existing technology weight is _ -~- -88.2 Kg. This shows that the invented technology is lighter by approximately 11 %.
Volume of space taken, including the frame construction: The invented technology occupies 82500 cm3 and the existing technology takes 51183 cm3 of space. Therefore, the invented model takes approximately 38% less space than the existing model.
Power densities: Two forms of power densities are compared. 1 ) Ratio of power to volume (VA I Volume); the invented technology has 0.59 ratio and the existing technology has 0.36 ratio. The invented model has 64%
better power density. 2) Ratio of power to weight (VA / Kg); the invented technology has 353 ratio and the existing technology has 275 ratio.
Therefore, the invented model has 28% more power density.
$ ._ A detailed description of the preferred embodiment is provided below with reference to the following:
Figures 1a and 1b show the pictorial drawings of the invented three-phase transformer and an existing EI three-phase transformer. The invented three-phase consists of three limbs, around which windings are wound, two tape-wound toroidal yokes and two fans. Each wound limb represents one phase of the three-phase system. The three wound limbs are positioned, equally spaced, around the surface of the toroidal yokes.
Two fans that blow air inside the tunnel are placed at both ends of the assembly.
In the existing E-I three-phase transformer, Figure 1a, the limbs are referred to that section of the stacked EI laminations around which the windings are wound, and yokes are referred to in the sections that join the limbs together.
Figure 2 shows the electric circuit analog of the magnetic circuit of an existing three-phase transformer, and the invented three-phase transformer. The battery voltage represents the winding magneto motive force (mmf or Ampere-Turn). Resistance R represents the reluctance of the air-gap between the limb and the yoke and the current I represents the generated magnetic flux.
Figure 3 shows a balanced three-phase excitation waveform. The graph demonstrates a three-phase excitation for a three-phase transformer, showing the level of the excitation at various moments in each cycle and also indicating that the sum of instantaneous voltages is equal to zero.
Figure 4 shows the outline of the air-tunnel and the forced-air flow in the invented three-phase transformer with fans placed at both ends of the transformer.
Figure 5 shows the picture of the 30KVA prototype of the invented three-phase transformer, which includes the transformer and the casing assembly.
Figure 6 compares the performance of the 30kVA invented three-phase prototype transformer with an existing off-the-shelf three-phase transformer.
Numbering of the described elements of the drawings 1 Limb
Claims (3)
1. A dry type Three-Phase Transformer with toroidal yoke which develops high power density (ratio of power to active volume) in the magnitude of 3.0 times the existing three phase technology.
2. A dry type Three Phase Transformer with toriodal yoke as defined in claim 1, of which the main component is a toroidal core, which is wound with continuous tape of grain oriented silicon steel (GOSS) with no gaps and all the grains orientated in a preferred direction, being used as a yoke in the structure of the transformer.
3. A dry type Three Phase Transformer with toriodal yoke as defined in claim 1 and 2, which provides more power density and less stray magnetic field by use of a different shape and design and occupies less space by use of a cylindrical shape.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2486767 CA2486767A1 (en) | 2004-11-26 | 2004-11-26 | Three phase transformer with dual toroidal flux return path |
| PCT/CA2005/001780 WO2006056057A1 (en) | 2004-11-26 | 2005-11-23 | Three-phase transformer with dual toroidal flux return path |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2486767 CA2486767A1 (en) | 2004-11-26 | 2004-11-26 | Three phase transformer with dual toroidal flux return path |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2486767A1 true CA2486767A1 (en) | 2006-05-26 |
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ID=36481068
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2486767 Abandoned CA2486767A1 (en) | 2004-11-26 | 2004-11-26 | Three phase transformer with dual toroidal flux return path |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA2486767A1 (en) |
| WO (1) | WO2006056057A1 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR101474205B1 (en) | 2011-07-08 | 2014-12-17 | 에이비비 리써치 리미티드 | Gas-insulated delta transformer |
| CA2859655A1 (en) * | 2011-12-19 | 2013-06-27 | Abb Technology Ag | Apparatus and method for cooling a transformer having a non-linear core |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| IL126748A0 (en) * | 1998-10-26 | 1999-08-17 | Amt Ltd | Three-phase transformer and method for manufacturing same |
| US20030206087A1 (en) * | 2002-05-06 | 2003-11-06 | Square D Company | Magnetic system having three-dimensional symmetry for three phase transformers |
-
2004
- 2004-11-26 CA CA 2486767 patent/CA2486767A1/en not_active Abandoned
-
2005
- 2005-11-23 WO PCT/CA2005/001780 patent/WO2006056057A1/en active Application Filing
Also Published As
| Publication number | Publication date |
|---|---|
| WO2006056057A1 (en) | 2006-06-01 |
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| FZDE | Dead |
Effective date: 20131018 |