A small and flexible auxiliary power supply circuit and method

Abstract

The present invention discloses a small and flexible auxiliary power supply circuit and method in the field of auxiliary circuits, including a transformer T. The transformer T includes primary windings TA, TB and N secondary windings (N≥1); among them, the grounds of M secondary windings are isolated from the grounds of any N-1 secondary windings (N≥M≥0); the same-name end of the primary winding TA is connected to the first end of a resistor R1, and the non-same-name end is connected to the collector of a switching triode V; the second end of the resistor R1 is connected to the base of the switching triode V, the first end of a first energy storage element C1 and the cathode of a voltage stabilizing diode ZD; the same-name end of the primary winding TB is connected to the second end of a resistor R2 and the cathode of a diode D0, and the non-same-name end is connected to the positive electrode of a second energy storage element C2 and the emitter of the switching triode V; the second end of the first energy storage element C1 is connected to the first end of the resistor R2. The present invention reduces the system volume, improves the system practicability, has a simple design, a simple and flexible structure, low cost, reliable operation, and has significant economic effects.

Description

Technical Field

[0001] The present invention relates to the field of auxiliary circuits, and specifically to a small and flexible auxiliary power supply circuit and method. Background Art

[0002] Currently, for internal auxiliary power supply in electronic system products at home and abroad, multiple isolated DC-DC converters are widely used to meet the auxiliary power supply requirements. Using this method, the output voltage is stable and reliable, with isolation function, but the volume is relatively large and the cost is relatively high.

[0003] In addition to the above method, there is also a method of using multiple non-isolated voltage chips for different voltage power supplies to meet the system's auxiliary power supply requirements. However, this method has a single output voltage, a complex structure, and a high cost.

[0004] In addition, there is also a method of using an isolated DC-DC converter in combination with a non-isolated voltage chip to further meet the auxiliary power supply requirements, but this method has a cumbersome variety.

[0005] With the rapid development of electronic technologies such as aerospace weapons and the improvement of system miniaturization, higher requirements are put forward for the functionalization and integration of the system's auxiliary power supply. Using the above several methods makes the system volume relatively large and the cost relatively high, and it cannot meet some occasions of low-cost miniaturized systems.

[0006] For the auxiliary power supply requirements of electronic products inside different electronic systems, there is no clear and in-depth research. Therefore, the applicant proposes an improved solution for the above technical background.

[0007] Method Content

[0008] The purpose of the present invention is to provide a small and flexible auxiliary power supply circuit and method to solve the problems raised in the above background art.

[0009] To achieve the above purpose, the present invention provides the following technical solutions:

[0010] A small and flexible auxiliary power supply circuit includes a transformer T. The transformer T includes a primary winding TA, a primary winding TB, and N secondary windings TCn (N≥1, n = 1, 2,..., N). One end of each secondary winding TCn is connected to a diode Dn respectively, and the other end is grounded respectively. Among them, the grounds of M secondary windings are isolated from the grounds of any N - 1 secondary windings (N≥M≥0). The primary winding TB includes a switching transistor V, a voltage regulator diode ZD, a diode D0, a first energy storage element C1, and a second energy storage element C2. The same - named end of the primary winding TA is connected to the first end of a resistor R1, and the non - same - named end is connected to the collector of the switching transistor V. The second end of the resistor R1 is connected to the base of the switching transistor V, the first end of the first energy storage element C1, and the cathode of the voltage regulator diode ZD. The same - named end of the primary winding TB is connected to the second end of a resistor R2 and the cathode of the diode D0, and the non - same - named end is connected to the positive electrode of the second energy storage element C2 and the emitter of the switching transistor V. The second end of the first energy storage element C1 is connected to the first end of the resistor R2, and the anode of the diode D0 is connected to the anode of the voltage regulator diode ZD and the negative electrode of the second energy storage element C2.

[0011] As an improved scheme of the present invention, a filter capacitor C is further connected between the two ends of the secondary winding TCn. n+2 .

[0012] The power supply method of the above - mentioned power supply circuit includes the following steps:

[0013] Step 1: Obtain the output voltage Un (1≤n≤N) required by the secondary winding TCn. At the same time, obtain the number of turns of the primary winding TB and the model parameters of each device in the primary windings TA and TB.

[0014] Step 2: Analyze the circuit to obtain the calculation formula for the output voltage Un:

[0015]

[0016] where, U ZD is the regulated voltage of the voltage regulator diode ZD; V BE is the BE voltage drop of the switching transistor V, V D0 is the forward voltage drop of the diode D0; V Dn is the forward voltage drop of the diode Dn; N B is the number of turns N of the primary winding TB B , and Nn is the set number of turns of the secondary winding TCn;

[0017] Step 3: Determine the number of turns of the secondary winding TCn according to the required output voltage Un.

[0018] Step 4: Judge whether the ground of the secondary winding TCn needs to be isolated: If so, execute Step 5; if not, execute Step 6;

[0019] Step 5: Set potential isolation for the ground of the secondary winding TCn;

[0020] Step 6: The secondary winding TCn outputs voltage Un.

[0021] Beneficial effects: The present invention can achieve different auxiliary power supply outputs only by changing the number of turns of the secondary winding and the regulated voltage value of the voltage regulator diode. Compared with the conventional method of using multiple transformers to meet the requirements of multiple auxiliary power supplies, the system volume is effectively reduced, the system practicability is improved, the design is simple, the structure is simple and flexible, the cost is low, the operation is reliable, and it has significant economic effects. Description of the Drawings

[0022] Figure 1 It is a schematic diagram of the principle of multi-output auxiliary power supply in the present invention;

[0023] Figure 2 It is a schematic diagram of the principle of dual-output non-isolated auxiliary power supply in the present invention;

[0024] Figure 3 It is a schematic diagram of the principle of dual-output isolated auxiliary power supply in the present invention;

[0025] Figure 4 It is a flowchart of the implementation method of the present invention;

[0026] Figure 5 It is a structural block diagram of an implementation example of the auxiliary power supply of a constant current power supply in the present invention;

[0027] Figure 6 It is a structural block diagram of an implementation example of the auxiliary power supply of a DC-DC converter in the present invention;

[0028] Figure 7 It is a structural block diagram of an implementation example of the auxiliary power supply of a servo control system in the present invention. Detailed Implementation Modes

[0029] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0030] See Figure 1, A small and flexible auxiliary power supply circuit, including a transformer T. The transformer T includes primary windings TA, TB and N secondary windings TCn (N≥1, n = 1, 2,..., N); one end of each secondary winding TCn is respectively connected with a diode Dn, and the other end is respectively grounded, and there are M secondary windings whose grounds are isolated from the grounds of any N - 1 secondary windings (N≥M≥0).

[0031] Specifically, when N = 1, there is only one secondary winding TC1 outputting voltage U1, and isolation is not required.

[0032] When N = 2, there are secondary windings TC1 and TC2 respectively outputting voltages U1 and U2. When M = 1, the grounds of secondary windings TC1 and TC2 are isolated, that is, the grounds are not connected together.

[0033] When N = 4 and M = 1, the ground of one of the secondary windings is isolated from the grounds of the other three secondary windings, and the grounds of these three non - isolated secondary windings are connected together to form a common terminal. When M = 2, the grounds of any two of the two secondary windings that need to be isolated are isolated from the grounds of the other three secondary windings. That is, the grounds of the two secondary windings that need to be isolated are set separately, and the grounds of the other two non - isolated secondary windings are connected.

[0034] Therefore, when there are M secondary windings that need to be isolated among N secondary windings, the ground of any one of the M secondary windings that need to be isolated is isolated from the grounds of the other N - 1 secondary windings.

[0035] Specifically, the primary winding TB includes a switching transistor V, a voltage - stabilizing diode ZD, a diode D0, a first energy - storage element C1 and a second energy - storage element C2; among them, both the first energy - storage element C1 and the second energy - storage element C2 are capacitors. The same - name end of the primary winding TA is connected to the first end of a resistor R1, and the non - same - name end is connected to the collector of the switching transistor V; the second end of the resistor R1 is connected to the base of the switching transistor V, the first end of the first energy - storage element C1 and the cathode of the voltage - stabilizing diode ZD.

[0036] The same - name end of the primary winding TB is connected to the second end of a resistor R2 and the cathode of the diode D0, and the non - same - name end is connected to the positive electrode of the capacitor C2 and the emitter of the switching transistor V; the second end of the first energy - storage element C1 is connected to the first end of the resistor R2, and the anode of the diode D0 is connected to the anode of the voltage - stabilizing diode ZD and the negative electrode of the second energy - storage element C2.

[0037] Specifically, the diode Dn is a rectifier diode, which is connected in series at the same - name end or non - same - name end of the secondary winding. A filter capacitor C is also connected between the two ends of the secondary winding. n+2 . When n = 1, that is, when there is only one secondary winding TC1, the diode Dn is D1, and the filter capacitor is C3.

[0038] The power supply method of the above power supply circuit, such as Figure 4 shown, includes the following steps:

[0039] Step 1: Obtain the output voltage Un (1 ≤ n ≤ N) required by the secondary winding TCn, and at the same time obtain the number of turns of the primary winding TB and the model parameters of each device in the primary windings TA and TB;

[0040] Step 2: Analyze the circuit to obtain the calculation formula for the output voltage Un:

[0041]

[0042] where U ZD is the regulated voltage of the zener diode ZD; V BE is the BE voltage drop of the switching transistor V, V D0 is the forward voltage drop of the diode D0; V Dn is the forward voltage drop of the diode Dn; N B is the number of turns N of the primary winding TB B , and Nn is the set number of turns of the secondary winding TCn;

[0043] Step 3: Determine the number of turns of the secondary winding TCn according to the required output voltage Un;

[0044] Step 4: Determine whether the ground of the secondary winding TCn needs to be isolated: If yes, execute Step 5; if no, execute Step 6;

[0045] Step 5: Set potential isolation for the ground of the secondary winding TCn. The isolated grounds can be achieved through capacitors, and the grounds that do not need to be isolated are directly connected.

[0046] Step 6: The secondary winding TCn outputs the voltage Un.

[0047] Example 1, taking a dual-output non-isolated auxiliary power supply circuit as an example, such as Figure 2 shown, when there are two secondary windings, they are called TC1 and TC2 in sequence. The diode connected to the secondary winding TC1 is D1, its anode is connected to the non-homonymous end of the secondary winding TC1, and its cathode is connected to the filter capacitor C3. The diode connected to the secondary winding TC2 is D2, its cathode is connected to the homonymous end of the secondary winding TC1, and its anode is connected to the filter capacitor C4.

[0048] By analyzing the circuit, its working principle can be obtained as follows:

[0049] (1) When the input voltage is connected, the resistor R1 provides a starting current for the switching transistor V, causing the switching transistor V to start conducting. The current I at its collector C CIt increases linearly in the primary winding TA, and a positive feedback voltage that makes the base B of the switching transistor V positive and the emitter E negative is induced in the primary winding TB, causing the switching transistor V to saturate quickly;

[0050] (2) At the same time, the induced voltage charges the capacitor C1. As the charging voltage of the capacitor C1 increases, the base potential of the switching transistor V gradually decreases, causing the switching transistor V to exit the saturation region, and the collector C current I C starts to decrease, and a voltage that makes the base B of the switching transistor V negative and the emitter E positive is induced in the primary winding TB, causing the switching transistor V to quickly cut off;

[0051] (3) When the switching transistor V is cut off, there is no induced voltage in the primary winding TB, and the DC input voltage charges the capacitor C1 reversely through the resistor R1, gradually increasing the base B potential of the switching transistor V, making it conduct again and flipping to the saturation state again, and the circuit oscillates repeatedly like this;

[0052] (4) When the switching transistor V is cut off, the diodes D1 and D2 at the secondary windings TC1 and TC2 conduct, and the energy stored in the primary winding of the transformer T is released to the load, outputting the voltages U1 and U2.

[0053] When the diode D1 conducts, the induced electromotive force of the secondary winding TC1 is positive at the top and negative at the bottom. Due to the relationship of the same-name terminals, the induced electromotive force of the primary winding TB is negative at the top and positive at the bottom, and the output voltage U1 is obtained as:

[0054]

[0055] At this time, the primary winding TB charges the capacitor C2 through the diode D0, and the withstand voltage value of the capacitor C2 should be at least greater than the regulated voltage value of the voltage regulator diode ZD. According to Figure 2 as shown by the arrow, it can be obtained that:

[0056] V TB =V C2 +V D0 (2)

[0057] V ZD =V BE +V C2 (3)

[0058] In the formula, NB and N1 are the number of turns of the primary winding TB and the secondary winding TC1 respectively; V D0 , V D1 , V BE , V ZD are the conduction voltage drop of the diode D0, the conduction voltage drop of the diode D1, the voltage drop between the BE of the switching transistor, and the regulated voltage value of the voltage regulator diode ZD respectively.

[0059] Combining formulas (1), (2), and (3), the output voltage U1 can be obtained as follows:

[0060]

[0061] Generalizing to N secondary windings, the output voltage Un of TCn can be obtained:

[0062]

[0063] Furthermore, if the voltage drops of V D0 、V Dn 、V BE are ignored, the output voltage Un can be simplified as:

[0064]

[0065] From the above analysis, it can be concluded that: when using this auxiliary power supply method, the output voltage is mainly related to the regulated voltage value of the zener diode ZD, the number of turns of the feedback winding TB, and the number of turns of the secondary winding.

[0066] In this embodiment, the output voltage U1 can be simplified as:

[0067]

[0068] Similarly, the output voltage U2 can be calculated as:

[0069]

[0070] In the formula, N2 is the number of turns of the secondary winding TC2.

[0071] As Figure 5 shown, when the constant current source circuit requires an auxiliary power supply voltage of 12V, a zener diode with a regulated voltage value of V ZD = 6V can be used. By the method in step 3, when the number of turns of the secondary winding TC1 and the number of turns of the secondary winding TC2 are both twice the number of turns of the feedback winding TB, that is, V ZD = 6V, the output voltage U1 and the output voltage U2 can be obtained:

[0072] U1 = 12V; U2 = -12V

[0073] At this time, it can be used as an auxiliary power supply circuit in the constant current power supply.

[0074] When the constant current source circuit requires an auxiliary power supply voltage of 15V, a zener diode with a regulated voltage value of V ZD = 7.5V can be used to make the number of turns of the secondary winding TC1 and the number of turns of the secondary winding TC2 both twice the number of turns of the feedback winding TB, that is, V ZD = 7.5V, When this occurs, the output voltage U1 and the output voltage U2 can be obtained as follows:

[0075] U1 = 15V; U2 = -15V

[0076] Example 2: Taking the realization of isolated dual-channel equal-voltage output as an example, as Figure 3 shown, the ground GND1 of the secondary winding TC1 is isolated from the ground GND2 of TC2. Similarly, it can be deduced that:

[0077] When using a zener diode with a regulated voltage value V ZD = 6V, when substituting into formulas (5) and (6), the isolated two-channel output voltages U1 and the output voltage U2 can be obtained:

[0078] U1 = 12V; U2 = -12V

[0079] As Figure 6 shown, when four groups of secondary windings TC1 to TC4 are set, and the turns ratio of the secondary windings of these four groups to the primary winding TB is 2, four isolated 12V voltages can be output to this DC-DC converter as an auxiliary power supply circuit.

[0080] When using a zener diode with a regulated voltage value V ZD = 7.5V, and the number of turns of the secondary winding TC1 and the number of turns of the secondary winding TC2 are both twice the number of turns of the feedback winding TB, substituting into formulas (5) and (6) can obtain the isolated two-channel output voltages U1 and the output voltage U2:

[0081] U1 = 15V; U2 = -15V

[0082] When using a zener diode with a regulated voltage value V ZD = 7.5V, when substituting into formulas (5) and (6), the isolated two-channel output voltages U1 and the output voltage U2 can be obtained:

[0083] U1 = 12V; U2 = -5V

[0084] Example 3: As Figure 7 shown, in this servo control system, the auxiliary power supply circuit has 6 outputs, that is, it includes a total of 6 secondary windings TC1 to TC6. At a regulated voltage value V ZDWhen the regulated voltage V = 7.5V, the secondary windings TC1 and TC2 need to output a voltage of 15V, and the turns ratio of these two secondary windings to the primary winding TB is 2; the secondary windings TC3 and TC4 need to output a voltage of 5V, and the turns ratio of these two secondary windings to the primary winding TB is 2∶3; the secondary windings TC5 and TC6 need to output a voltage of 12V, and the turns ratio of these two secondary windings to the primary winding TB is 8∶5.

[0085] When the regulated voltage value V ZD = 6V, the secondary windings TC1 and TC2 need to output a voltage of 15V, and the turns ratio of these two secondary windings to the primary winding TB is 5∶2; the secondary windings TC3 and TC4 need to output a voltage of 5V, and the turns ratio of these two secondary windings to the primary winding TB is 5∶6; the secondary windings TC5 and TC6 need to output a voltage of 12V, and the turns ratio of these two secondary windings to the primary winding TB is 2.

[0086] When the number of turns of the primary winding TB is fixed and the turns ratio of the secondary winding TCn to the primary winding TB is not an integer, at this time, rectifying diodes Dn with different forward voltage drops can be selected, and the forward voltage drop value of the diode Dn is used to make the auxiliary voltage output reach the expected value.

[0087] There is no need to isolate between the output voltages U1 and U2 and between U5 and U6, so the ground potentials of the secondary windings TC1 and TC2 are equal, and the ground potentials of TC5 and TC6 are equal. The output voltages U3, U4, and U5 need to be isolated, so the ground of the secondary winding TC3 is isolated from the grounds of the other 5 secondary windings. Similarly, the grounds of the secondary windings TC4 and TC5 are also isolated from the grounds of any other 5 secondary windings.

[0088] It can be seen that when more output channels are required, the parameter values of the devices can be selected, the number of secondary windings can be increased, the number of turns of the secondary winding can be selected according to the required output voltage, or different voltages can be output by changing the regulated voltage value of the zener diode ZD. By selecting zener diodes ZD with different regulated voltage values, changing the turns ratio of different feedback windings TB and secondary windings TCn, and adopting different connection methods for the output GND, multiple auxiliary power supply voltages with different functions can be flexibly output. Moreover, since only one transformer is used, the volume and weight are also reduced, making it more suitable for miniaturized applications.

[0089] Although this specification is described according to the embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0090] In the description of the present invention, it should be noted that relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, invention, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or elements inherent to such process, invention, article or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, invention, article or device comprising said element.

[0091] In the description of the present invention, it should also be noted that unless otherwise clearly specified and limited, the terms "arranged" and "connected" should be understood in a broad sense. For example, they can be directly connected or indirectly connected through an intermediate medium, and can be the internal connection of two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0092] Therefore, the above description is only the preferred embodiment of the present application and is not used to limit the scope of implementation of the present application; that is, all equivalent transformations made according to the scope of the claims of the present application are within the protection scope of the claims of the present application.

Claims

1. A small and flexible auxiliary power supply circuit, comprising a transformer T, characterized in that: The transformer T includes primary windings TA and TB and N secondary windings TCn, where N ≥ 1 and n = 1, 2, ..., N. One end of each secondary winding TCn is connected to a diode Dn, and the other end is grounded. The grounds of the M secondary windings are isolated from the grounds of any N-1 secondary windings, where N ≥ M ≥ 0. The primary winding TB includes a switching transistor V, a voltage regulator diode ZD, a diode D0, a first energy storage element C1 and a second energy storage element C2; The same-name end of the primary winding TA is connected to the first end of the resistor R1, and the non-same-name end is connected to the collector of the switching transistor V; the second end of the resistor R1 is connected to the base of the switching transistor V, the first end of the first energy storage element C1 and the cathode of the voltage-stabilizing diode ZD; The same-name end of the primary winding TB is connected to the second end of the resistor R2 and the cathode of the diode D0, and the non-same-name end is connected to the positive electrode of the second energy storage element C2 and the emitter of the switching transistor V; the second end of the first energy storage element C1 is connected to the first end of the resistor R2, and the anode of the diode D0 is connected to the anode of the voltage regulator diode ZD and the cathode of the second energy storage element C2; A filter capacitor C is also connected between the two ends of the secondary winding TCn. n+2 ; The power supply method of the small and flexible auxiliary power supply circuit comprises the following steps: Step 1: Obtain the output voltage Un required by the secondary winding TCn, where 1≤n≤N. Also obtain the number of turns of the primary winding TB and the model parameters of each component in the primary windings TA and TB. Step 2: Analyze the circuit and obtain the calculation formula for the output voltage Un: Among them, U ZD is the stabilizing voltage of the Zener diode ZD; V BE is the BE voltage drop of the switching transistor V, V D0 is the forward voltage drop of diode D0; V Dn is the forward voltage drop of diode Dn; N B is the number of turns N of the primary winding TB B , Nn is the number of turns of the set secondary winding TCn; Step 3: Determine the number of turns of the secondary winding TCn according to the required output voltage Un; Step 4: Determine whether the ground of the secondary winding TCn needs to be isolated: if yes, go to step 5; if no, go to step 6; Step 5: Set potential isolation for the ground of the secondary winding TCn; Step 6: The secondary winding TCn outputs the voltage Un.

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