METHODS AND CONFIGURATIONS OF LC COMBINED TRANSFORMERS AND EFFECTIVE UTILIZATIONS OF CORES THEREIN

• US 20100001822A1
• Filed: 07/02/2008
• Published: 01/07/2010
• Est. Priority Date: 07/02/2008
• Status: Active Grant

• Current Assignee: Chun Li, Jason Li, Ran Ran Li
• Original Assignee: Chun Li, Jason Li, Ran Ran Li
• Inventors: Li, Chun, Li, Jason (Jian Hao), Li, Ran Ran
• Granted Patent: US 9,257,225 B2
• Time in Patent Office: Days
• US Class Current: 336/105
• CPC Class Codes: H01F 27/385 for reducing harmonics
• CPC Class Codes: H01F 3/12 Magnetic shunt paths
• CPC Class Codes: H01F 38/16 Cascade transformers, e.g. for use with extra high tension

Abstract

This invention presents the LC combined transformer, a combination of capacitances, inductances and an electrically-isolated mutual inductor, i.e. conventional transformer. To improve the imperfections of the widely-used transformers, by means of the simplest passive-circuit design of perfectly-functionally mating mutual capacitors with the mutual inductor, the invention achieves optimal characteristics of current or/and voltage conversions, with a new property of waveform conversion from square-wave to quasi-sinusoid. The ideal current transformers herein are suited to sinusoidal current measurements, the ideal voltage transformers suited to sinusoidal voltage measurements, and they all could be upgraded to ideal transformers, capable of current and voltage conversions. They can also be designed as both power transferable and waveform convertible, applicable in power electronics. Herein also states the design approach of integrated inductor and mutual inductor and the usage of push-pull inductor, materials being fully utilized and sizes greatly decreased.

Claims

1. A species of electrical transformer, termed LC combined transformer, for transferring electric signal or/and energy of periodical sinusoid or periodic wave at least, and linearly altering the magnitudes of voltage or/and current, which is characterized as:

consisting of some linear capacitances, linear inductances and an linear mutual inductor (i.e. the conventional transformer);

said mutual inductor'"'"'s leakage inductances and magnetization inductance combined with said capacitances and/or said inductances so as to constitute at least one unity-coupled mutual capacitors;

said mutual capacitor being a two-port electrical network of a Δ

or T or their variant and equivalent configuration of at least three in total said capacitances and/or said inductances;

when neglecting power loss, said unity-coupled Δ

(or π

) mutual capacitor exhibiting a characteristic of pure current conversion between ports, and/or said unity-coupled T (or Y) mutual capacitor exhibiting a characteristic of pure voltage conversion between ports;

and, between said at least one unity-coupled mutual capacitors and between some of them and the ideal transformer peeled off said leakage inductances and magnetization inductance from said mutual inductor there existing relations of electrical connection in cascade one after another.

2. The LC combined transformer defined in claim 1, whereof the design scheme of a practical and generalized circuit configuration (FIG. 2), which is described as:

comprising one or two said unity-coupled mutual capacitors cascade-connected to said ideal transformer of said mutual inductor, consisting of two said linear inductances, three said linear capacitances and one said linear mutual inductor, with its electrical connections stated as follows;

one end of the first said inductance designated as input terminal, the other end connected with one end of the first said capacitance and also one end of the second said inductance, the other end of the second inductance connected with one end of the second said capacitance and also one end of the third said capacitance, the other end of second capacitance connected to one terminal of the primary winding of said mutual inductor, the other end of first capacitance and the other end of third capacitance together connected with the other terminal of said primary winding as well as designated as common terminal, defining said input terminal and said common terminal as input port of the LC combined transformer, defining the two terminals of the secondary winding of said mutual inductor as its output port;

with that the position of third capacitance could be moved to and connected in parallel with said input port or output port when necessary, that the positions of second inductance and second capacitance could be switched to each other when the third capacitance not connected to the junction between second inductance and second capacitance, that the designation or definition of said input port and said output port could be interchanged according to necessity, and that the sequence or orders between said cascade-connections of two said unity-coupled mutual capacitors and said ideal transformer could be altered as long as the altered version is electrically equivalent to the circuit presented herein.

3. The LC combined transformer defined in claim 2, whereof said linear inductances, capacitances and mutual inductor all being real components with power loss (FIG. 2(c)) although their magnitude values could be separately produced by the principle of series-parallel equivalence, with their values ranged and characterized as:

said first and second inductances respectively being definitely-valued or zero-valued (short-circuited), said first capacitance definitely-valued, said second capacitance definitely-valued or indefinitely-valued (short-circuited), said third capacitance definitely-valued or zero-valued (open-circuited), the self-inductances of both primary and secondary windings of said mutual inductor definitely-valued respectively;

said linearity of real components meaning proximately linear of satisfying the requirements of conversion precision of said transformer;

and, that said mutual inductor might be multi-winding on condition that it can be electrically equalized as a double-winding and employed within this invention.

4. The LC combined transformer defined in claim 3, whereof the first embodiment referred to as current conversion-A type LC combined transformer, or in short as conversion-A ideal current transformer or ideal current transformer A (FIG. 3), is described as:

consisting of said mutual inductor of two windings with self-inductances definitely-valued respectively, said first capacitance definitely-valued, said second inductance definitely-valued, said first inductance and second capacitance short-circuited, and said third capacitance open-circuited;

with designations of the winding connected with said inductance and capacitance as the secondary of said mutual inductor, of the other winding as its primary and also as input port of this embodiment, and of the two terminals of said first capacitance as the output port.

5. The current conversion-A type LC combined transformer defined in claim 4, wherein two current conversions performed by the cascade-connected said ideal transformer of said mutual inductor and one unity-coupled Δ

(or π

) mutual capacitor, is characterized as;

said mutual capacitor exhibiting a characteristic of pure current conversion between ports when neglecting power loss and designed as according with the condition ω

²C_m(L₂+L_b)=1 (Eq.

     9), with a result of this transformer'"'"'s port current ratio as

$\begin{array}{cc}\frac{I_1}{I_2}=\frac{n_c}{n}=\frac{1}{\mathrm{nk}}<br><br>\left(1+\frac{L_b}{L_2}\right),& \left(\mathrm{Eq}.<br><br>11\right)\end{array}$

where C_m is the value of said first capacitance, L₂ the self-inductance value of said secondary winding of said mutual inductor, L_b the value of said second inductance, and ω

the electrical angular frequency/velocity of said periodic wave applied to this transformer, I₁ the rms value of sinusoidal current entering said input port, I₂ the rms value of sinusoidal current leaving said output port, k the coupling coefficient of said mutual inductor, n the ratio of said mutual inductor equal to its turns ratio of said primary winding to said secondary winding, and n_c the current ratio of input port to output port of said unity-coupled Λ

(or π

) mutual capacitor.

6. Performance of the integration design approach of an inductor and a mutual inductor, developed from the current conversion-A type LC combined transformer defined in claim 4, turning out a multi-purpose integrated inductor and mutual inductor (FIGS. 3(c) and (d)) which is characterized as:

comprising the core magnetic circuit of said mutual inductor, the core magnetic circuit of said inductor, the primary winding of said mutual inductor, the two-in-one common coil served both as the secondary winding of said mutual inductor and also as the winding of said inductor, and the auxiliary winding (set when needed) of said inductor;

said primary winding of said mutual inductor being wound around just said core magnetic circuit of said mutual inductor with its two terminals treated as input port, said common coil wound around the paralleled and adjacent-to-each-other portions of both said core magnetic circuit of said mutual inductor and that of said inductor, said auxiliary winding wound around just said core magnetic circuit of said inductor, and said common coil and said auxiliary winding connected series-aiding with the terminals after series as output port;

the cores of said mutual inductor and said inductor being possibly made from any available magnetic material, shaped as any realizable appearances and styles, cross-sectional areas probably unequal to each other, and magnetic circuit lengths maybe different from each other;

designations of said input port and said output port being interchangeable when needed;

and, the turns ratio, the coupling coefficient, the primary self-inductance, the secondary self-inductance, and relations of currents and powers all being determined as for those of conventional mutual inductors, while the total output inductance being almost the sum of said secondary self-inductance of said mutual inductor and the inductance determined by all together of said common coil, said auxiliary winding and said magnetic circuit of said inductor provided with said magnetic circuits in a qualified linearity.

7. The LC combined transformer defined in claim 3, whereof the second embodiment referred to as current conversion-B type LC combined transformer, or in short as conversion-B ideal current transformer or ideal current transformer B (FIG. 4), is described as:

consisting of said mutual inductor of two windings with self-inductances definitely-valued respectively, said first and second capacitances both definitely-valued, said first and second inductances both short-circuited, and said third capacitance open-circuited;

with designations of the winding connected with said capacitances as the secondary of said mutual inductor, of the other winding as its primary and also as input port of this embodiment, and of the two terminals of said first capacitance as the output port.

8. The current conversion-B type LC combined transformer defined in claim 7, wherein two current conversions performed by the cascade-connected said ideal transformer of said mutual inductor and one unity-coupled Δ

(or π

) mutual capacitor, is characterized as;

said mutual capacitor exhibiting a characteristic of pure current conversion between ports when neglecting power loss and designed as according with the condition

${\mathrm{\omega <br><br>}}^2<br><br>L_2<br><br>\left(\frac{C_b<br><br>C_m}{C_b+C_m}\right)=1$

(Eq.

     19), with a result of this transformer'"'"'s port current ratio as

$\begin{array}{cc}\frac{I_1}{I_2}=\frac{n_c}{n}=\frac{C_b}{\mathrm{nk}<br><br>\left(C_b+C_m\right)},& \left(\mathrm{Eq}.<br><br>21\right)\end{array}$

where C_m is the value of said first capacitance, C_b the value of said second capacitance, L₂ the self-inductance value of said secondary winding of said mutual inductor, and ω

the electrical angular frequency/velocity of said periodic wave applied to this transformer, I₁ the rms value of sinusoidal current entering said input port, I₂ the rms value of sinusoidal current leaving said output port, k the coupling coefficient of said mutual inductor, n the ratio of said mutual inductor equal to its turns ratio of said primary winding to said secondary winding, and n_c the current ratio of input port to output port of said unity-coupled Δ

(or π

) mutual capacitor.

9. The LC combined transformer defined in claim 3, whereof the third embodiment referred to as in-phase mode voltage conversion type LC combined transformer, or in short as in-phased ideal voltage transformer (FIG. 5), is described as:

consisting of said mutual inductor of said primary and secondary windings with self-inductances definitely-valued respectively, said first inductance definitely-valued, said first and second capacitances both definitely-valued, said second inductance short-circuited, and said third capacitance open-circuited.

10. The in-phase mode voltage conversion type LC combined transformer defined in claim 9, wherein three voltage conversions performed by the cascade-connected said ideal transformer of said mutual inductor and two unity-coupled T (or Y) mutual capacitors, is characterized as:

said two unity-coupled mutual capacitors each exhibiting a characteristic of pure voltage conversion between ports when neglecting power loss and designed as according with the conditions ω

²L_a(C_b1+C_m)=1 (Eq.

     27) and ω

²(1−

k²)L₁C_b2=1 (Eq.

     37), with a result of this transformer'"'"'s port voltage ratio as

$\begin{array}{cc}\frac{V_1}{V_2}=\frac{{\mathrm{knC}}_{b<br><br><br><br>1}}{C_{b<br><br><br><br>1}+C_m},& \left(\mathrm{Eq}.<br><br>44\right)\end{array}$

where L_a is the value of said first inductance, L₁ the self-inductance value of said primary winding of said mutual inductor, C_m the value of said first capacitance, C_b1 and C_b2 respectively the values of the first and the second of two series components of said second capacitance C_b or

$C_b=C_{b<br><br><br><br>1}\perp <br><br>C_{b<br><br><br><br>1}=\frac{C_{b<br><br><br><br>1}<br><br>C_{b<br><br><br><br>2}}{C_{b<br><br><br><br>1}+C_{b<br><br><br><br>2}},$

ω

the electrical angular frequency/velocity of said periodic wave applied to this transformer, V₁ and V₂ the rms values of sinusoidal voltages across said input port and said output port respectively, k the coupling coefficient of said mutual inductor, and n the ratio of said mutual inductor equal to its turns ratio of said primary winding to said secondary winding.

11. The LC combined transformer defined in claim 3, whereof the fourth embodiment referred to as anti-phase mode voltage conversion type LC combined transformer, or in short as anti-phased ideal voltage transformer (FIG. 6), is described as:

consisting of said mutual inductor of said primary and secondary windings with self-inductances definitely-valued respectively, said first inductance definitely-valued, said second inductance definitely-valued or short-circuited in case, said first capacitance definitely-valued, said second capacitance definitely-valued or short-circuited in case, and said third capacitance open-circuited or definitely-valued when needed.

12. The anti-phase mode voltage conversion type LC combined transformer defined in claim 11, wherein three voltage conversions performed by the cascade-connected said ideal transformer of said mutual inductor and two unity-coupled T (or Y) mutual capacitors, is characterized as:

said two unity-coupled mutual capacitors each exhibiting a characteristic of pure voltage conversion between ports when neglecting power loss and designed as according with the conditions ω

²C_m(L_a//L_b)=1 (Eq.

     46) and ω

²(1−

k²)L₁C_b=1 (Eq.

     37), with a result of this transformer'"'"'s port voltage ratio as

$\begin{array}{cc}\frac{V_1}{V_2}=-\mathrm{kn}<br><br>\frac{L_a}{L_b},& \left(\mathrm{Eq}.<br><br>53\right)\end{array}$

where L_a is the value of said first inductance, L_b the value of said second inductance, L₁ the self-inductance value of said primary winding of said mutual inductor, C_m the value of said first capacitance, C_b the value of said second capacitance, ω

the electrical angular frequency/velocity of said periodic wave applied to this transformer, V₁ and V₂ the rms values of sinusoidal voltages across said input port and said output port respectively, k the coupling coefficient of said mutual inductor, and n the ratio of said mutual inductor equal to its turns ratio of said primary winding to said secondary winding.

13. Usage of the push-pull inductor (illustrated in FIG. 11(b)), developed for the in-phase mode voltage conversion type LC combined transformer defined in claim 9, which includes:

{circle around (1)} one center-tapped inductor 1a, two electrically-symmetric driving switches such as transistors depicted as 31 and 33 [Note;

neither positive logic nor bipolar junction transistors (BJTs) is the only choice for this application though both are employed in the circuit of the example herein], and two electrically-symmetric passive switches such as diodes 32 and 34;

{circle around (2)} one end of inductor 1a electrically connected to collector of transistor 31 and also to anode of diode 32, the other end to collector of transistor 33 and also to anode of diode 34, emitters of transistors 31 and 33 both connected together to the reference potential, cathodes of diodes 32 and 34 both connected together to a high potential, bases of transistors 31 and 33 respectively connected to corresponding control-and-driving signals, and the center-tap of inductor la connected to an appropriate high potential;

{circle around (3)} the push-pull inductor employing a technique of the bi-periodically time-shared driving.

14. Technique of the bi-periodically time-shared driving, cited in claim 13, whereby a pair of electrically-symmetric driving switches such as transistors depicted as 31 and 33 in FIG. 11(b) of a double-ended circuit are driven with their bases or control-in terminals both separately applied with the control-and-driving signals as those like P1 and P2 shown in FIG. 11(c), which can be described as:

a pulse-width modulation (PWM) control and driving with two periods as a cycle of a sequence as stated as follows;

switch 33 being off for the first period while switch 31 on not longer than T/2 before turning off;

for the second period switch 31 being off while switch 33 on not longer than T/2 before turning off, with the end of second period as the end of a cycle of the bi-periodically time-shared driving;

where T is the time of switch operating period of the circuit.

15. A two-port network component, termed unity-coupled Δ

(or π

) mutual capacitor or current type mutual capacitor, described in claim 1, multi-purposely used for ac circuits, is characterized as;

having its equivalent circuit configuration, the most simplified electrically, of three capacitances in Δ

(or π

) connections (see FIG. IV-3);

exhibiting a characteristic of pure current conversion between ports when neglecting power loss;

and, according with the unity-coupled condition that the sum of all three reciprocal values of said capacitances is zero (refer to Eq. IV-22) where the needed negative capacitances may be realized through negative impedance converters or by employing inductances operating at a constant frequency.

16. A two-port network component, termed unity-coupled T (or Y) mutual capacitor or voltage type mutual capacitor, described in claim 1, multi-purposely used for ac circuits, is characterized as:

having its equivalent circuit configuration, the most simplified electrically, of three capacitances in T (or Y) connections (see FIG. IV-4);

exhibiting a characteristic of pure voltage conversion between ports when neglecting power loss;

and, according with the unity-coupled condition that the sum of all three values of said capacitances is zero (refer to Eq. IV-24) where the needed negative capacitances may be realized through negative impedance converters or by employing inductances operating at a constant frequency.