Auxiliary power supply circuit and charging system

Abstract

The utility model discloses an auxiliary power supply circuit and a charging system, and relates to the field of power electronics. The auxiliary power supply circuit comprises a control chip and a transformer. The transformer comprises a magnetic core, at least one primary winding, at least two secondary windings and a self-feeding winding; wherein the self-feeding winding and part of the secondary winding are sleeved on the magnetic core at intervals along the axial direction of the magnetic core, and the rest of the secondary winding and the primary winding are sequentially sleeved on the outer side of the self-feeding winding along the radial direction of the magnetic core; and one end of the self-feeding winding is connected with a power supply pin of the control chip, and the other end of the self-feeding winding is grounded. Therefore, the output short-circuit protection function is realized under the condition that an additional circuit is not added.

Description

Technical Field

[0001] The present application relates to the field of power electronics, and in particular to an auxiliary power supply circuit and a charging system. Background Art

[0002] As the power demand of charging piles gradually increases, the size of the power module in the charging module is also gradually increasing, which causes the position of the auxiliary power supply and the fan in the charging module to be farther and farther away, so that the auxiliary power supply and the fan power supply port need to be connected through a long PCB trace. However, the use environment of charging piles is diverse. If the charging pile is used in a relatively harsh environment for a long time, the probability of the auxiliary power supply short circuit will greatly increase. Therefore, the auxiliary power supply needs to have an output short-circuit protection function.

[0003] At present, the main way to achieve the output short-circuit protection function is to add an external circuit. However, if an external circuit is to be added, it will inevitably cause problems such as increased cost, increased PCB layout space, and reduced overall machine reliability. Summary of the invention

[0004] The main purpose of the present application is to provide an auxiliary power supply circuit and a charging system to achieve output short-circuit protection function without adding an external circuit.

[0005] To achieve the above-mentioned purpose, the present application provides an auxiliary power supply circuit, including a control chip and a transformer;

[0006] The transformer comprises a magnetic core, at least one primary winding, at least two secondary windings and a self-fed winding; wherein the self-fed winding and part of the secondary windings are sleeved on the magnetic core at intervals along the axial direction of the magnetic core, and the remaining secondary windings and the primary windings are sequentially sleeved on the outside of the self-fed winding along the radial direction of the magnetic core;

[0007] One end of the self-feeding winding is connected to the power pin of the control chip, and the other end of the self-feeding winding is grounded.

[0008] Optionally, the secondary winding includes a main and secondary winding and at least two secondary windings; the self-fed winding is sleeved on the middle position of the magnetic core, a part of the secondary winding is sleeved on the top of the magnetic core, and another part of the secondary winding is sleeved on the bottom of the magnetic core, and the self-fed winding and the secondary winding are wound in the same layer; the main and secondary windings are sleeved on the outside of the self-fed winding along the radial direction of the magnetic core, and the primary winding is sleeved on the outside of the main and secondary windings along the radial direction of the magnetic core.

[0009] Optionally, the secondary winding includes a first secondary winding, a second secondary winding and a third secondary winding; the first secondary winding is wound at the top position of the magnetic core, the self-fed winding is wound at the middle position of the magnetic core, and the second secondary winding and the third secondary winding are wound at the bottom position of the magnetic core.

[0010] Optionally, the secondary winding includes a first secondary winding, a second secondary winding and a third secondary winding; the second secondary winding and the third secondary winding are wound at the top position of the magnetic core, the self-fed winding is wound at the middle position of the magnetic core, and the first secondary winding is wound at the bottom position of the magnetic core.

[0011] Optionally, the auxiliary power supply circuit also includes a first loop, a second loop and a driving unit, and the primary winding includes a first primary winding and a second primary winding; the first primary winding is connected in series in the first loop, and the second primary winding is connected in series in the second loop; the input end of the driving unit is connected to the driving pin of the control chip, and the output end of the driving unit is respectively connected to the first loop and the second loop.

[0012] Optionally, the first circuit includes a first capacitor, a first switching tube, a first diode and a resistor; one end of the first capacitor is connected to one end of the first primary winding, the other end of the first primary winding is connected to the anode of the first diode, and the cathode of the first diode is connected to the first electrode of the first switching tube; the control electrode of the first switching tube is connected to the driving unit, and the second electrode of the first switching tube is connected to one end of the resistor; the other end of the resistor is connected to the other end of the first capacitor to form a first node.

[0013] Optionally, the second circuit includes a second capacitor, a mutual inductor, a second switching tube and a second diode; one end of the second capacitor is connected to the first node, one end of the mutual inductor is connected to the first node, the other end of the mutual inductor is connected to one end of the second primary winding, and the other end of the second primary winding is connected to the first pole of the second switching tube; the control pole of the second switching tube is connected to the driving unit, the second pole of the second switching tube is connected to the anode of the second diode, and the cathode of the second diode is connected to the other end of the second capacitor and grounded.

[0014] Optionally, the auxiliary power supply circuit also includes a third diode; the cathode of the third diode is connected to the power pin of the control chip, the anode of the third diode is connected to one end of the self-feed winding, and the other end of the self-feed winding is connected to the ground pin of the control chip and grounded.

[0015] Optionally, the auxiliary power supply circuit also includes multiple rectifier circuits, and each secondary winding is respectively on each rectifier circuit; the rectifier circuit includes a rectifier diode and an output capacitor, one end of the secondary winding is connected to the anode of the rectifier diode, the cathode of the rectifier diode is connected to one end of the output capacitor, and the other end of the output capacitor is connected to the other end of the secondary winding.

[0016] In addition, to achieve the above-mentioned purpose, the present application also provides a charging system, comprising an auxiliary power supply circuit as described in any one of the above, and a control module, a communication module, a drive module and a fan respectively connected to the auxiliary power supply circuit; the auxiliary power supply circuit is used to supply power to the control module, the communication module, the drive module and the fan.

[0017] The auxiliary power supply circuit of the present application is achieved by spacing the self-fed winding and part of the secondary winding of the transformer on the magnetic core, and setting the remaining secondary winding between the primary winding and the self-fed winding, that is, the self-fed winding and the primary winding are isolated by the secondary winding, so that the coupling relationship between the self-fed winding and the primary winding is weakened, so that it is easier for the control chip to achieve hiccup restart, and then realize the short-circuit protection function. Therefore, the short-circuit protection function can be achieved only by changing the winding method of the transformer winding, without adding additional circuits, thereby reducing costs, reducing the space occupied by devices, and ensuring the overall reliability of the charging system. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a schematic diagram of a circuit board layout of a charging system according to an embodiment of the present application;

[0019] Figure 2 is a schematic diagram of an auxiliary power supply circuit of an embodiment of the present application;

[0020] Figure 3 is a schematic diagram of a transformer winding structure according to an embodiment of the present application;

[0021] Figure 4 is a schematic diagram of a transformer winding structure of a specific example of the present application;

[0022] Figure 5 is a schematic diagram of a transformer winding structure of another specific example of the present application;

[0023] Figure 6 is a schematic structural diagram of a charging system according to an embodiment of the present application;

[0024] In the figure: 110, control chip; 120, transformer; 121, magnetic core; 122, primary winding; 123, secondary winding; 124, self-fed winding; 130, first circuit; 140, second circuit; 150, drive unit; 600, charging system; 610, auxiliary power supply circuit; 620, control module; 630, communication module; 640, drive module; 650, fan; 660, power module.

[0025] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of this application clearer, the technical solutions in this application will be clearly and completely described below in conjunction with the drawings in this application. Obviously, the described embodiments are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0027] At present, the field of electric vehicles is developing rapidly. Charging piles are used as power supplement equipment for electric vehicles, and their core components are charging systems. Based on various considerations such as the cost and volume of charging piles, the most commonly used heat dissipation method for charging systems is air cooling. Therefore, the charging system needs to have an auxiliary power supply that can work continuously and reliably. In the charging system, the auxiliary power supply provides energy for the control unit, communication unit, fan, etc. in the entire charging system.

[0028] In the charging system, the auxiliary power supply and each module are connected and output power through an interface, wherein the output port of the auxiliary power main circuit is also provided with an electrolytic capacitor, and the electrolytic capacitor of the auxiliary power main circuit is connected to each fan port through a plug-in terminal. As the charging demand of electric vehicles gradually increases, the charging power increases from 10Kw, 20kw, 30kw to the current 40kw and 60kw, so that the size of the power module in the charging system gradually increases to meet the charging demand, thereby increasing the area of ​​the single-board PCB (Printed Circuit Board).

[0029] Figure 1 Schematic diagram of the circuit board layout of the charging system of the embodiment of the present application. Figure 1As shown, from the perspective of the reasonable planning and arrangement of the entire board space, the fan needs to be set at the position of the entire module air inlet. Since the drive circuit needs to drive the fan and the power module, the drive circuit needs to be set between the fan and the power module, and the power module will release a lot of heat when working, so the power module needs to be set close to the air inlet and the fan. This results in the auxiliary power supply being set only at a position far away from the fan, resulting in a long PCB trace being required between the auxiliary power supply and the fan power supply connector port, and the electrolytic capacitor output terminal of the auxiliary power main circuit and the fan plug-in terminal being exposed.

[0030] However, the use environment of charging piles is diverse, and wet dust pollution and salt spray corrosion are inevitable. At the same time, fan failure and device failure will significantly increase the probability of auxiliary power output short circuit. When a short circuit occurs, in order to avoid explosion, explosion sound, system downtime and to improve customer satisfaction, the charging system auxiliary power supply must have an output short circuit protection function.

[0031] The current common way to achieve the output short-circuit protection function is to use an external circuit. Specifically, the output voltage or output current of the auxiliary power main circuit is detected by an external circuit, and a control signal is output to the COMP pin of the main control chip based on the output voltage or output current, so that the level value of the COMP pin is reduced, thereby making the main control chip have no drive output; when there is no voltage in the self-feeding winding, the startup loop is not enough to maintain the normal operation of the auxiliary power control chip, and the level of the VCC pin of the control chip begins to decrease. When the level of the VCC pin of the control chip decreases to the shutdown point of the control chip, the control chip shuts down, and then the startup loop restarts to charge the VCC capacitor of the control chip to complete the protection of the hiccup mode.

[0032] However, if short-circuit protection in hiccup mode is achieved by adding an external circuit, it is necessary to add resistors, capacitors, diodes, transistors, current sampling resistors, current sampling CTs or optocouplers, etc. This will inevitably increase the cost and PCB layout space. At the same time, the increase in components will also affect the reliability of the whole machine to a certain extent. Therefore, it is urgent to find a new way to implement the output short-circuit protection function of the auxiliary power supply of the charging system.

[0033] To this end, an embodiment of the present application provides an auxiliary power supply circuit and a charging system. By improving the winding structure of the transformer in the auxiliary power supply circuit, the coupling between the self-fed winding and the primary winding that supplies power to the control chip is weakened, thereby reducing the electric energy of the self-fed winding, and then reducing the input voltage of the control chip, thereby realizing the output short-circuit protection function without the need for additional circuits.

[0034] Figure 2 is a schematic diagram of an auxiliary power supply circuit of an embodiment of the present application, Figure 3 It is a schematic diagram of the transformer winding structure of an embodiment of the present application.

[0035] like Figure 2 and Figure 3 As shown, the auxiliary power supply of the embodiment of the present application may include a control chip 110 and a transformer 120; the transformer 120 includes a magnetic core 121, at least one primary winding 122, at least two secondary windings 123 and a self-fed winding 124; wherein the self-fed winding 124 and part of the secondary windings 123 are arranged on the magnetic core 121 along the axial direction of the magnetic core 121, and the remaining secondary windings 123 and the primary winding 122 are arranged in sequence on the outside of the self-fed winding 124 along the radial direction of the magnetic core 121; one end of the self-fed winding 124 is connected to the power pin of the control chip 110, and the other end of the self-fed winding 124 is grounded.

[0036] For ease of understanding, let's first combine Figure 2 The principle of achieving the short-circuit protection function by changing the winding structure of the transformer 120 in the embodiment of the present application is explained.

[0037] When the auxiliary power supply is short-circuited, short-circuit protection can be performed through hiccup protection. Hiccup protection is a protection mechanism for short-circuit and overload conditions, mainly used to protect the power supply and load from damage; hiccup protection distinguishes between permanent short-circuit faults and temporary faults by periodically trying to restart the circuit. Its specific working principle is: first detect whether the circuit is short-circuited or overloaded. When the circuit detects a short circuit or overload, the protection mechanism will be triggered; next, the power supply output is turned off to cut off the current and prevent further damage; further, the power supply enters a short waiting period (usually a few seconds to tens of seconds), during which the power supply will not output any current; after the delay period, the power supply will try to start the output again to check whether the short circuit or overload condition still exists; if the short circuit or overload condition still exists, the power supply will turn off the output again and repeat the above process, forming a periodic restart attempt, just like a person hiccups, so it is called "hiccup protection".

[0038] It can be known from the working principle of the hiccup protection that when the auxiliary power supply is short-circuited, the control chip 110 of the auxiliary power supply needs to be turned off first, and the control chip 110 is powered by the self-feeding winding 124 in the transformer 120, so when a short circuit occurs, the induced voltage of the self-feeding winding 124 can be rapidly reduced, so that the input voltage of the control chip 110 is reduced to the shutdown point, and the control chip 110 is shut down. However, in actual use, the transformer 120 is not an ideal transformer, and there is a leakage inductance between the primary winding 122 and the self-feeding winding 124, so the higher the input voltage of the primary winding 122, the greater the output energy of the self-feeding winding 124, so that when the auxiliary power supply circuit is short-circuited, the VCC pin of the control chip 110 cannot drop below the undervoltage protection voltage, so that the control chip 110 cannot hiccup and restart to achieve short-circuit protection, and then a large current flows through the power device for a long time, causing it to burn.

[0039] It should be noted here that the primary winding 122 is the main winding of the transformer 120, which is responsible for receiving alternating current from the main power supply and generating a magnetic field; the self-fed winding 124 can induce a voltage from the magnetic field of the transformer 120, thereby providing an additional auxiliary power supply; there is a coupling relationship between the primary winding 122 and the self-fed winding 124, and the coupling relationship will affect the magnitude of the induced voltage of the self-fed winding 124. Generally, if the degree of coupling between the primary winding 122 and the self-fed winding 124 is higher, the greater the electric energy of the primary winding 122, the greater the induced voltage generated by the self-fed winding 124.

[0040] Therefore, the degree of coupling between the primary winding 122 and the self-fed winding 124 can be reduced by improving the winding structure of the transformer 120. Even if the primary winding 122 has a large electric energy, the induced voltage of the self-fed winding 124 is still small. Therefore, when a short circuit occurs, the self-fed winding 124 can quickly reduce the induced voltage and reduce it to the shutdown point of the control chip 110.

[0041] Based on the above principles, the auxiliary power supply circuit of the embodiment of the present application will be introduced in detail below.

[0042] In this embodiment, the transformer 120 may include a magnetic core 121, a plurality of primary windings 122, a plurality of secondary windings 123, and a self-feed winding 124. It should be noted that, in the analog circuit, the primary winding 122 refers to a winding arranged at the primary side of the transformer 120, the secondary winding 123 refers to a winding arranged at the secondary side of the transformer 120, and the self-feed winding 124 is a winding in the transformer 120 that provides or receives energy through its own induced voltage, and the self-feed winding 124 is usually arranged at the primary side of the transformer 120.

[0043] Specifically, part of the secondary windings 123 can be selected from all the secondary windings 123, and these part of the secondary windings 123 and the self-fed winding 124 can be sleeved on the magnetic core 121 along the axial direction of the magnetic core 121, and the self-fed winding 124 can be set in the middle position of these part of the secondary windings 123, so that the secondary winding 123 serves as a retaining wall for the self-fed winding 124. The remaining secondary windings 123 can be sleeved on the outside of the self-fed winding 124, and the axial position of the remaining secondary windings 123 is the same as the axial position of the self-fed winding 124, which is equivalent to the remaining secondary windings 123 being wound around the periphery of the self-fed winding 124; further, all the primary windings 122 can be sleeved on the outside of the remaining secondary windings 123, and the axial position of the primary windings 122 is the same as the axial position of the remaining secondary windings 123.

[0044] Therefore, all the secondary windings 123 surround the self-fed winding 124, and the secondary windings 123 can be regarded as the retaining wall of the self-fed winding 124, so that the coupling relationship between the primary winding 122 and the self-fed winding 124 is weaker. When the auxiliary power supply is short-circuited, the energy transferred from the primary winding 122 to the self-fed winding 124 will be even less, causing the output voltage of the self-fed winding 124 to be reduced, which is more conducive to the realization of hiccup protection.

[0045] In some embodiments, the secondary winding 123 includes a primary secondary winding 123 and at least two secondary secondary windings 123. The self-feeding winding 124 is sleeved in the middle of the magnetic core 121, a portion of the secondary secondary windings 123 is sleeved on the top of the magnetic core 121, and another portion of the secondary secondary windings 123 is sleeved on the bottom of the magnetic core 121, and the self-feeding winding 124 and the secondary secondary windings 123 are wound in the same layer; the primary secondary windings 123 are sleeved on the outside of the self-feeding winding 124 along the radial direction of the magnetic core 121, and the primary winding 122 is sleeved on the outside of the primary secondary windings 123 along the radial direction of the magnetic core 121.

[0046] It should be noted that, in the secondary winding 123 of the transformer 120, there is usually a main output winding, and the main output winding is usually the winding with the largest output current. Based on this, the main and secondary windings 123 described in this embodiment are the main output windings with the largest output current, or the secondary winding 123 with the largest wire diameter can be selected as the main and secondary windings 123, and the remaining secondary windings 123 are the secondary and secondary windings 123 described in this embodiment.

[0047] In addition, the number of the primary winding 122 and the secondary winding 123 can be determined according to actual needs and is not specifically limited here.

[0048] It is understandable that when the auxiliary power supply is short-circuited, the duty cycle of the primary conduction needs to be very small, so as to reduce the heat generation power borne by the power device and the PCB wiring when the short circuit occurs, which requires a high degree of coupling between the primary winding 122 and the secondary winding 123 of the transformer 120. If the coupling degree between the primary winding 122 and the secondary winding 123 is high, when the auxiliary power supply is short-circuited, the energy transferred from the primary winding 122 to the secondary winding 123 will be greater, so that the electric energy of the primary winding 122 is quickly reduced, thereby reducing the heat generation power of the power device and the PCB wiring.

[0049] Therefore, in this embodiment, the secondary winding 123 with a smaller output current can be used as a retaining wall of the self-fed winding 124, so that the coupling degree between the self-fed winding 124 and the primary winding 122 is relatively low; the secondary winding 123 with a maximum or larger output current can be used as the main-secondary winding 123, and the coupling degree between the primary winding 122 and the main-secondary winding 123 is relatively high, thereby not only reducing the voltage of the self-fed winding 124, but also reducing the heating power and heating time of the power device, thereby better realizing the short-circuit protection function.

[0050] Specifically, the self-fed winding 124 can be wound at the middle position of the magnetic core 121; all the secondary windings 123 are divided into two parts, and are arranged on the upper and lower sides of the self-fed winding 124 respectively, and the secondary windings 123 and the self-fed winding 124 are wound in one layer. At this time, the secondary winding 123 is equivalent to the function of the retaining wall, which reduces the coupling ability of the primary winding 122 and the self-fed winding 124. In addition, the main and secondary windings 123 can be wound on the outside of the self-fed winding 124 along the radial direction of the magnetic core 121, that is, the main and secondary windings 123 and the self-fed winding 124 are wound on different layers, but the axial position of the main and secondary windings 123 is the same as the axial position of the self-fed winding 124; all the primary windings 122 are then wound on the outside of the main and secondary windings 123 in sequence, that is, the main and secondary windings 123 and each primary winding 122 are wound on different layers. At this time, the main and secondary windings 123 are also equivalent to the function of the retaining wall, which further reduces the coupling ability of the primary winding 122 and the self-fed winding 124.

[0051] The winding structure of the transformer 120 is further described in detail below through two embodiments.

[0052] Figure 4 It is a schematic diagram of a transformer winding structure of a specific example of the present application.

[0053] like Figure 4As shown, in some embodiments, the secondary winding 123 may include a first secondary winding N7, a second secondary winding N3, and a third secondary winding N5; the first secondary winding N7 is wound at the top position of the magnetic core 121, the self-fed winding 124 is wound at the middle position of the magnetic core 121, and the second secondary winding N3 and the third secondary winding N5 are wound at the bottom position of the magnetic core 121.

[0054] It should be noted that Figure 4 TS represents the number of turns of the high-temperature tape, 2.5 mm and 3.5 mm represent the thickness of the retaining wall, TOP represents the top of the magnetic core 121, PIN represents the pin of the transformer 120, and BOBBIN is the coil skeleton. The above are all commonly used symbols in the winding diagram of the transformer 120 and will not be described here.

[0055] In this embodiment, the transformer 120 includes a total of 7 windings, namely: a first primary winding N1, a second primary winding N2, a self-fed winding N4, a primary-secondary winding N6, a first secondary winding N7, a second secondary winding N3 and a third secondary winding N5.

[0056] refer to Figure 4 The specific winding method of the transformer 120 can be: the first secondary winding N7, the second secondary winding N3, the third secondary winding N5, and the self-feeding winding N4 are wound in one layer, and the windings are arranged at intervals without overlapping each other. Specifically, the second secondary winding N3 and the third secondary winding N5 are wound in single strands at the bottom of the magnetic core 121 (PIN side in the figure) near the pin of the transformer 120, the self-feeding winding N4 is wound in double strands at the middle position of the magnetic core 121, and the first secondary winding N7 is wound in double strands at the top of the magnetic core 121 (TOP side in the figure), so that the first secondary winding N7 and the second secondary winding N3 / third secondary winding N5 are respectively located at the two ends of the self-feeding winding N4, and a retaining wall of 3.5mm to 4mm is added on both sides.

[0057] Furthermore, the main and secondary windings N6 can be wound on the outer layer of the self-fed winding N4, and the main and secondary windings N6 are also located in the middle of the magnetic core 121, and the main and secondary windings N6 are not in the same layer as the self-fed winding N4. Finally, the first primary winding N1 and the second primary winding N2 can be wound on the outside of the main and secondary windings N6 in sequence, that is, the first primary winding N1, the second primary winding N2 and the main and secondary windings N6 are respectively in different layers, and the first primary winding N1 and the second primary winding N2 are also in the middle of the magnetic core 121. In addition, a 3.5mm to 4mm retaining wall can be added at both ends of the main and secondary windings N6, and a 2.5mm to 3.5mm retaining wall can be added at both ends of the first primary winding N1 and the second primary winding N2.

[0058] Therefore, the transformer 120 is wound in a sandwich structure as a whole, the primary winding 122 and the secondary winding 123 are wound around the magnetic core 121 at intervals, and the primary and secondary windings N6, the first secondary winding N7, the second secondary winding N3, and the third secondary winding N5 all have a certain barrier effect, which effectively reduces the coupling ability of the self-fed winding N4 with the first primary winding N1 and the second primary winding N2.

[0059] It should be noted that the transformer 120 winding method described above is adopted, and its corresponding analog circuit diagram can be referred to Figure 2 shown.

[0060] Figure 5 It is a schematic diagram of the winding structure of the transformer 120 of another specific example of the present application.

[0061] like Figure 5 As shown, in some embodiments, the secondary winding 123 includes a first secondary winding N7, a second secondary winding N3, and a third secondary winding N5; the second secondary winding N3 and the third secondary winding N5 are wound at the top position of the magnetic core 121, the self-fed winding 124 is wound at the middle position of the magnetic core 121, and the first secondary winding N7 is wound at the bottom position of the magnetic core 121.

[0062] Similarly, in this embodiment, the transformer 120 includes a total of 7 groups of windings, namely: a first primary winding N1, a second primary winding N2, a self-fed winding N4, a primary-secondary winding N6, a first secondary winding N7, a second secondary winding N3 and a third secondary winding N5.

[0063] refer to Figure 5 , which is different from the winding method in the first example: the first secondary winding N7, the second secondary winding N3, the third secondary winding N5, and the self-feeding winding N4 are wound in one layer, and are arranged at intervals without overlapping each other. Specifically, the second secondary winding N3 and the third secondary winding N5 are wound in parallel on the top of the magnetic core 121 (TOP side in the figure), the self-feeding winding N4 is wound in parallel in two strands at the middle position of the magnetic core 121, and the first secondary winding N7 is wound in parallel in two strands at the bottom of the magnetic core 121 (PIN side in the figure) near the pin of the transformer 120, so that the first secondary winding N7 and the second secondary winding N3 / third secondary winding N5 are respectively located at the two ends of the self-feeding winding N4, and a retaining wall of 3.5mm to 4mm is added on both sides.

[0064] The winding methods of the first primary winding N1 , the second primary winding N2 , and the primary and secondary windings N6 are the same as those in the above-mentioned embodiment, and will not be described in detail herein.

[0065] It should be noted that when the winding method of the transformer 120 described in the second embodiment is adopted, the corresponding analog circuit diagram can be referred to Figure 2 As shown, just Figure 2 The positions of the first secondary winding N7 and the second secondary winding N3 / the third secondary winding N5 can be swapped.

[0066] It is worth mentioning that in this embodiment, the turns ratio of each primary winding 122 and each secondary winding 123 can be dynamically adjusted according to actual needs such as heat dissipation and the coupling of the primary and secondary windings to adjust the cross-regulation rate of the windings.

[0067] The above is a detailed introduction to the winding method of the transformer 120. The following takes the winding method of the transformer 120 described in the first embodiment as an example to introduce the auxiliary power supply circuit and the short-circuit protection function in detail.

[0068] Continue to refer Figure 2 and Figure 4 In some embodiments, the auxiliary power supply circuit further includes a first loop 130, a second loop 140 and a driving unit 150, and the primary winding 122 includes a first primary winding N1 and a second primary winding N2; the first primary winding N1 is connected in series to the first loop 130, and the second primary winding N2 is connected in series to the second loop 140; the input end of the driving unit 150 is connected to the driving pin DRV of the control chip 110, and the output end of the driving unit 150 is connected to the first loop 130 and the second loop 140 respectively.

[0069] It should be noted that the drive unit 150 may use an existing auxiliary power drive circuit, and the specific structure of the drive unit 150 is not the focus of this application, and the structure of the drive unit 150 is not introduced here. Figure 4 N6-1 and N6-2 are both main and secondary windings, and the main and secondary windings N6-1 and N6-2 can be connected in series or in parallel; similarly, the first primary windings N1-1 and N1-2 can be connected in series or in parallel, and the second primary windings N2-1 and N2-2 can also be connected in series or in parallel.

[0070] Specifically, the first loop 130 and the second loop 140 are both power loops, the first primary winding N1 is connected in series to the first loop 130, and the first primary winding N1 is used to store the electric energy input from the first loop 130; the second primary winding N2 is connected in series to the second loop 140, and the second primary winding N2 is used to store the electric energy input from the second loop 140. The input end of the drive unit 150 is connected to the drive pin DRV of the control chip 110, and the control chip 110 controls the charging and discharging of the auxiliary power supply by outputting a drive signal (a high level signal or a low level signal) to the drive unit 150.

[0071] In some embodiments, the first loop 130 includes a first capacitor C1 , a first switch Q1 , a first diode D1 , and a resistor R1 .

[0072] Among them, one end of the first capacitor C1 is connected to one end of the first primary winding N1, the other end of the first primary winding N1 is connected to the anode of the first diode D1, and the cathode of the first diode D1 is connected to the first electrode of the first switch tube Q1; the control electrode of the first switch tube Q1 is connected to the driving unit 150, and the second electrode of the first switch tube Q1 is connected to one end of the resistor R1; the other end of the resistor R1 is connected to the other end of the first capacitor C1, and forms a first node N1.

[0073] It should be noted that the first switch tube Q1 and the subsequent second switch tube Q2 can both be MOS tubes, wherein the control electrode of the first switch tube Q1 can be the gate of the MOS tube, the first electrode of the first switch tube Q1 can be the source of the MOS tube, the second electrode of the first switch tube Q1 can be the drain of the MOS tube, and the second switch tube Q2 is the same as the first switch tube Q1.

[0074] In some embodiments, the second loop 140 includes a second capacitor C2, a transformer CT, a second switch tube Q2, and a second diode D2.

[0075] Among them, one end of the second capacitor C2 is connected to the first node N1, one end of the transformer CT is connected to the first node N1, the other end of the transformer CT is connected to one end of the second primary winding N2, and the other end of the second primary winding N2 is connected to the first pole of the second switch tube Q2; the control pole of the second switch tube Q2 is connected to the driving unit 150, the second pole of the second switch tube Q2 is connected to the anode of the second diode D2, the cathode of the second diode D2 is connected to the other end of the second capacitor C2, and the cathode of the second diode D2 and the other end of the second capacitor C2 are grounded.

[0076] In some embodiments, the auxiliary power supply circuit also includes a third diode D3; the cathode of the third diode D3 is connected to the power pin VCC of the control chip 110, the anode of the third diode D3 is connected to one end of the self-feed winding 124, the other end of the self-feed winding 124 is connected to the ground pin GND of the control chip 110, and the other end of the self-feed winding 124 is grounded to the ground pin GND of the control chip 110.

[0077] In this embodiment, the first capacitor C1 and the second capacitor C2 are electrolytic capacitors on the input side of the auxiliary power supply circuit, and the first capacitor C1 and the second capacitor C2 are connected to the main power supply at both ends, and the first capacitor C1 and the second capacitor C2 are used to store the electric energy input by the main power supply. The first switch tube Q1 and the second switch tube Q2 are both used to control the charging or discharging of the auxiliary power supply circuit; specifically, when the driving unit 150 controls the first switch tube Q1 and the second switch tube Q2 to be turned on, the first capacitor C1 and the second capacitor C2 will be discharged to the first primary winding N1 and the second primary winding N2 respectively, and the first primary winding N1 and the second primary winding N2 store electric energy, and when the driving unit 150 controls the first switch tube Q1 and the second switch tube Q2 to be turned off, the first capacitor C1 and the second capacitor C2 stop discharging to the first primary winding N1 and the second primary winding N2, and at this time, the first primary winding N1 and the second primary winding N2 release electric energy to each secondary winding 123 and the self-feed winding N4.

[0078] In this embodiment, the first diode D1, the second diode D2 and the third diode D3 are all used for reverse protection, and the resistor R1 in the first loop 130 and the transformer CT in the second loop 140 are used to detect the current of the primary main circuit.

[0079] Continue to refer Figure 2 In some embodiments, the auxiliary power supply circuit also includes multiple rectifier circuits, and each secondary winding 123 is respectively on each rectifier circuit; the rectifier circuit includes a rectifier diode Dz and an output capacitor Cz, one end of the secondary winding 123 is connected to the anode of the rectifier diode Dz, the cathode of the rectifier diode Dz is connected to one end of the output capacitor Cz, and the other end of the output capacitor Cz is connected to the other end of the secondary winding 123.

[0080] It should be noted that the output capacitor Cz is the output electrolytic capacitor of the secondary side in the auxiliary power circuit, which is used to power the control chip 110, power tube, communication module, etc. in the charging system. In addition, the rectifier diode plays a rectifying role as the name implies.

[0081] Specifically, in the present embodiment, the structures of the rectifier circuits are the same. Taking the first secondary winding N7 as an example, one end of the first secondary winding N7 is connected to the anode of the rectifier diode Dz, the cathode of the rectifier diode Dz is connected to one end of the output capacitor Cz, and the other end of the output capacitor Cz is connected to the other end of the first secondary winding N7.

[0082] The output short-circuit protection principle of the auxiliary power supply circuit of this embodiment is specifically as follows: when the auxiliary power supply circuit needs to work normally, the control chip 110 controls the driving unit 150 to output a high-level signal, and the high-level signal is transmitted to the first switch tube Q1 and the second switch tube Q2, so that the first switch tube Q1 and the second switch tube Q2 are turned on, and the first capacitor C1 and the second capacitor C2 discharge to the first primary winding N1 and the second primary winding N2.

[0083] When the auxiliary power supply circuit is short-circuited, the control chip 110 controls the driving unit 150 to output a low-level signal, and the low-level signal is transmitted to the first switch tube Q1 and the second switch tube Q2, so that the first switch tube Q1 and the second switch tube Q2 are turned off, and the first capacitor C1 and the second capacitor C2 stop discharging to the first primary winding N1 and the second primary winding N2, and the first primary winding N1 and the second primary winding N2 release electrical energy to the first secondary winding N7, the second secondary winding N3, the third secondary winding N5, the main and secondary windings N6 and the self-fed winding N4.

[0084] Since the degree of coupling between the self-fed winding N4 and the first primary winding N1 and the second primary winding N2 is relatively low, the induced voltage generated by the self-fed winding N4 is relatively low, so that the voltage input from the self-fed winding N4 to the control chip 110 can be quickly reduced. Finally, the voltage input from the self-fed winding N4 to the control chip 110 drops to the shutdown point, and the control chip 110 shuts down, which is more conducive to achieving hiccup protection.

[0085] In addition, when the auxiliary power supply circuit is short-circuited, the primary side of the auxiliary power supply circuit has a large short-circuit current. However, since the main-secondary winding N6 is highly coupled with the first primary winding N1 and the second primary winding N2, the main-secondary winding N6 can receive more electrical energy, so that the short-circuit current of the primary side of the auxiliary power supply circuit is quickly reduced, and the duty cycle of the two primary switch tubes is reduced, thereby reducing the heat power borne by the power devices and PCB traces.

[0086] It is worth mentioning that the design method and idea of ​​the transformer 120 winding can be used for the auxiliary source circuit using the VCC power supply winding as short-circuit hiccup protection. Different transformer 120 structures need to be optimized according to the idea in combination with actual conditions for the winding method and winding process. The design method of the transformer 120 winding provided in this embodiment not only meets the short-circuit protection function, but also takes into account the heat dissipation and the cross adjustment rate of the winding.

[0087] Therefore, the auxiliary power supply circuit of the embodiment of the present application can realize the short-circuit protection function by changing the winding structure of the transformer 120 in the auxiliary power supply circuit without adding additional circuits, and the short-circuit protection performance is better, which reduces the increase in device cost brought about by realizing the short-circuit protection function, reduces the occupied PCB space, and improves the reliability of the whole machine.

[0088] Figure 6 It is a schematic diagram of the structure of the charging system of an embodiment of the present application.

[0089] Based on the above embodiment, the present application embodiment further provides a charging system 600. Figure 6 As shown, the charging system 600 may include the auxiliary power circuit 610 as described above, and a control module 620, a communication module 630, a drive module 640, and a fan 650 respectively connected to the auxiliary power circuit 610; the auxiliary power circuit 610 is used to supply power to the control module 620, the communication module 630, the drive module 640, and the fan 650. In addition, the auxiliary power circuit 610 also includes a power module 660, and the drive module 640 is connected to the power module 660.

[0090] In this embodiment, the power module 660 is used to convert AC power into the electric energy required for charging the electric vehicle; the communication module 630 is used for the charging system to exchange information with the system main monitoring module; the control module 620 is used to control the drive module 640; the drive module 640 executes the instructions of the control module 620 and drives the power tube to enable the charging system to complete power conversion. The auxiliary power supply circuit 610 supplies power to the communication module 630, the cooling fan 650, the control module 620 and the drive module 640.

[0091] It should be noted that for details not disclosed in the charging system of this embodiment, please refer to the details disclosed in the embodiment of the auxiliary power supply circuit in the embodiment of this specification, which will not be repeated here.

[0092] The above are only preferred embodiments of the present application, and are not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. An auxiliary power supply circuit, characterized in that: Including control chip and transformer; The transformer comprises a magnetic core, at least one primary winding, at least two secondary windings and a self-fed winding; wherein the self-fed winding and part of the secondary windings are sleeved on the magnetic core at intervals along the axial direction of the magnetic core, and the remaining secondary windings and the primary windings are sequentially sleeved on the outside of the self-fed winding along the radial direction of the magnetic core; One end of the self-feeding winding is connected to the power pin of the control chip, and the other end of the self-feeding winding is grounded.

2. The auxiliary power supply circuit according to claim 1, characterized in that: The secondary winding comprises a primary secondary winding and at least two secondary secondary windings; The self-feeding winding is sleeved at the middle position of the magnetic core, a part of the secondary winding is sleeved at the top of the magnetic core, and another part of the secondary winding is sleeved at the bottom of the magnetic core, and the self-feeding winding and the secondary winding are wound in the same layer; The main and secondary windings are sleeved on the outer side of the self-feed winding along the radial direction of the magnetic core, and the primary winding is sleeved on the outer side of the main and secondary windings along the radial direction of the magnetic core.

3. The auxiliary power supply circuit according to claim 2, characterized in that: The secondary winding includes a first secondary winding, a second secondary winding and a third secondary winding; The first secondary winding is wound at the top position of the magnetic core, the self-feeding winding is wound at the middle position of the magnetic core, and the second secondary winding and the third secondary winding are wound at the bottom position of the magnetic core.

4. The auxiliary power supply circuit according to claim 2, characterized in that: The secondary winding includes a first secondary winding, a second secondary winding and a third secondary winding; The second secondary winding and the third secondary winding are wound at the top of the magnetic core, the self-feeding winding is wound at the middle of the magnetic core, and the first secondary winding is wound at the bottom of the magnetic core.

5. The auxiliary power supply circuit according to claim 1, characterized in that: The auxiliary power supply circuit further includes a first loop, a second loop and a driving unit, and the primary winding includes a first primary winding and a second primary winding; The first primary winding is connected in series to the first loop, and the second primary winding is connected in series to the second loop; The input end of the driving unit is connected to the driving pin of the control chip, and the output end of the driving unit is connected to the first loop and the second loop respectively.

6. The auxiliary power supply circuit according to claim 5, characterized in that: The first loop includes a first capacitor, a first switch tube, a first diode and a resistor; One end of the first capacitor is connected to one end of the first primary winding, the other end of the first primary winding is connected to the anode of the first diode, and the cathode of the first diode is connected to the first electrode of the first switch tube; The control electrode of the first switch tube is connected to the driving unit, and the second electrode of the first switch tube is connected to one end of the resistor; The other end of the resistor is connected to the other end of the first capacitor to form a first node.

7. The auxiliary power supply circuit according to claim 6, characterized in that: The second loop includes a second capacitor, a mutual inductor, a second switch tube and a second diode; One end of the second capacitor is connected to the first node, one end of the mutual inductor is connected to the first node, the other end of the mutual inductor is connected to one end of the second primary winding, and the other end of the second primary winding is connected to the first electrode of the second switch tube; The control electrode of the second switch tube is connected to the driving unit, the second electrode of the second switch tube is connected to the anode of the second diode, and the cathode of the second diode is connected to the other end of the second capacitor and is grounded.

8. The auxiliary power supply circuit according to claim 1, characterized in that: The auxiliary power supply circuit also includes a third diode; The cathode of the third diode is connected to the power pin of the control chip, the anode of the third diode is connected to one end of the self-feeding winding, and the other end of the self-feeding winding is connected to the ground pin of the control chip and is grounded.

9. The auxiliary power supply circuit according to claim 1, characterized in that: The auxiliary power supply circuit further includes a plurality of rectifier circuits, and each of the secondary windings is respectively on each of the rectifier circuits; The rectifier circuit includes a rectifier diode and an output capacitor, one end of the secondary winding is connected to the anode of the rectifier diode, the cathode of the rectifier diode is connected to one end of the output capacitor, and the other end of the output capacitor is connected to the other end of the secondary winding.

10. A charging system, characterized in that: The auxiliary power supply circuit comprises the auxiliary power supply circuit as claimed in any one of claims 1 to 9, and a control module, a communication module, a drive module and a fan respectively connected to the auxiliary power supply circuit; The auxiliary power supply circuit is used to supply power to the control module, the communication module, the drive module and the fan.

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