Auxiliary power supply circuit
By connecting four transistors in a circuit structure, the conduction and cutoff conditions of the transistors are controlled, which solves the problems of high cost and poor stability of the existing auxiliary power supply, realizes low-cost and efficient auxiliary power supply output, and ensures the stable operation of key equipment.
Patent Information
- Application Number
- CN202422798232.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-18
- Publication Date
- 2025-10-03
- Estimated Expiration
- 2034-11-18
AI Technical Summary
Existing auxiliary power systems are costly and prone to fluctuations, and the single-switch flyback topology causes voltage spikes and high-frequency ringing, affecting system stability and reliability.
A circuit structure with four transistors connected is adopted. By controlling the conduction and cutoff conditions of the transistors, voltage reduction is achieved to obtain a stable 12V auxiliary power output.
It achieves low-cost and efficient auxiliary power output, improves system reliability and stability, and ensures the normal operation of key equipment under abnormal circumstances.
Smart Images
Figure CN223414794U_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of power electronics technology, and in particular to an auxiliary power supply circuit. Background Art
[0002] In modern power systems, auxiliary power supplies are used to provide the energy required for control, protection, and monitoring equipment. They are typically independent of the primary power system and are used to ensure the continued operation of critical equipment during main power failures or other abnormal conditions. Auxiliary power supplies play a vital role in various industrial, commercial, and public facilities, and their output stability impacts the reliability and stability of the entire system.
[0003] Most current auxiliary power supplies utilize a single-switch flyback topology. When the MOSFET is on, energy is stored in the transformer's primary winding. The transformer's secondary is blocked by a diode, and the load is powered by the secondary's output capacitor. When the MOSFET is off, the primary voltage across the MOSFET exceeds the input voltage plus the output voltage reflected from the secondary winding. During this period, the secondary-side diode conducts, clamping the voltage across the transformer's primary to approximately the reflected output voltage. The turn-off event interrupts current flow through the transformer's primary winding, causing a voltage spike across the MOSFET. This voltage spike resonates with stray circuit capacitance and generates high-amplitude, high-frequency ringing. This resonance is suppressed by an RCD clamp / snubber circuit. Silicon carbide MOSFETs offer higher voltage margins, thus allowing for lower snubber losses. The snubber capacitor must be large enough to absorb leakage energy while maintaining low voltage ripple. The resulting DC power supply is used to power the control circuitry, sensing circuitry, and cooling fan. This auxiliary power supply solution is costly and susceptible to fluctuations. Utility Model Content
[0004] In view of the above-mentioned deficiencies in the prior art, the present application provides an auxiliary power supply circuit.
[0005] According to one aspect of the present application, an auxiliary power supply circuit is provided, comprising: a first transistor, a second transistor, a third transistor, and a fourth transistor, wherein the C-pole of the first transistor is connected to the C-pole of the second transistor, the B-pole of the third transistor is connected to the C-pole of both the first transistor and the C-pole of the second transistor, and the B-pole of the fourth transistor is connected to the C-pole of the third transistor via an inductor; the voltage is reduced by controlling the on / off conditions of the transistors, thereby obtaining a 12V auxiliary power supply.
[0006] In one embodiment of the present application, a parallel diode group is connected between the B pole of the second transistor, the E pole of the second transistor, and the E pole of the fourth transistor, and the E pole of the fourth transistor is connected to a voltage-stabilizing diode. When the circuit is working, when the voltage of the E pole of the first transistor is greater than the voltage of the B pole, the first transistor is turned on, there is a voltage difference between the upper and lower parts of the parallel diode group, the second transistor is turned on, the voltage of the B pole of the third transistor is 0, the third transistor is turned on, and the current is output to the outside after passing through the inductor. When the voltage rises to 12V, the fourth transistor and the voltage-stabilizing diode are turned on, and current forms a path after passing through the diode and the capacitor, pulling down the voltage of the B pole at the second transistor. At this time, the second transistor is turned off, and the third transistor is turned off. After that, the voltage drops below 12V and the cycle is repeated until the voltage is output stably.
[0007] An auxiliary power supply circuit provided in an embodiment of the present application includes: a first transistor, a second transistor, a third transistor, and a fourth transistor. The C-pole of the first transistor is connected to the C-pole of the second transistor, the B-pole of the third transistor is connected to the C-pole of both the first and second transistors, and the B-pole of the fourth transistor is connected to the C-pole of the third transistor via an inductor. The voltage is reduced by controlling the on / off conditions of the transistors to obtain a 12V auxiliary power supply. In this solution, by connecting four transistors and controlling the on / off conditions of the transistors to obtain a stable 12V auxiliary power output, the reliability of the entire power supply system can be increased. This solution has the positive effects of simplicity, high efficiency, and low cost. BRIEF DESCRIPTION OF THE DRAWINGS
[0008] Other features, objects and advantages of the present invention will become more apparent from the detailed description of the non-limiting embodiments with reference to the following drawings:
[0009] Figure 1 A schematic structural diagram of an auxiliary power supply circuit provided in a specific embodiment of the present utility model;
[0010] Among them, D5 diode, L3 inductor, C140 capacitor, C34 electrolytic capacitor, R18 resistor, D13 diode, C28 capacitor, R30 resistor, D20 diode, R190 resistor, Q22 second transistor, Q9 first transistor, Q21 third transistor, R221, R19 resistor, R85 resistor, C83 capacitor, L4 power inductor, D25 diode, C83 capacitor, D11 diode, C65 capacitor, C67 capacitor, C141 electrolytic capacitor, R90 resistor, ZD1 Zener diode, R86 resistor, Q13 fourth transistor. DETAILED DESCRIPTION
[0011] Auxiliary power is a common power supply circuit. In modern power systems, it provides the energy required for control, protection, and monitoring equipment. It is typically independent of the primary power system and is used to ensure that critical equipment continues to operate normally in the event of a primary power failure or other abnormal conditions. Auxiliary power supplies play a vital role in various industrial, commercial, and public facilities, improving system reliability and stability.
[0012] Most current auxiliary power supplies use a single-switch flyback topology. When the MOSFET is on, energy is stored in the transformer's primary winding. The transformer's secondary is blocked by a diode, and the load is powered by the secondary's output capacitor. When the MOSFET is off, the primary voltage across the MOSFET exceeds the input voltage plus the reflected output voltage from the secondary winding. During this period, the secondary-side diode conducts, clamping the voltage across the transformer's primary to approximately the reflected output voltage. The turn-off event interrupts current flow through the transformer's primary winding, causing a voltage spike across the MOSFET. This voltage spike resonates with stray circuit capacitance and produces high-amplitude, high-frequency ringing. This resonance is suppressed by an RCD clamp / snubber circuit. Silicon carbide MOSFETs offer higher voltage margins, thus allowing for lower snubber losses. The snubber capacitor must be large enough to absorb leakage energy while maintaining low voltage ripple, ultimately providing DC power for control circuits, sensing circuits, cooling fans, and other components. Based on this, embodiments of the present application provide an auxiliary power supply circuit. This solution is described in detail below through specific examples.
[0013] The present application provides an auxiliary power supply circuit. This circuit, as a battery-started auxiliary power supply, does not adopt the above design and does not use a single-switch flyback topology. It uses four transistors to control the circuit and is started by battery voltage to power the control circuit, sensor circuit, and cooling fan, etc., with the advantages of simplicity, high efficiency, and low cost.
[0014] Reference Figure 1 In the embodiment shown, an auxiliary power supply circuit is provided in this embodiment, including: a first transistor Q9, a second transistor Q22, a third transistor Q21, and a fourth transistor Q13. The C-pole of the first transistor is connected to the C-pole of the second transistor Q22, the B-pole of the third transistor Q21 is connected to the C-pole of the first transistor Q9 and the C-pole of the second transistor Q22, and the B-pole of the fourth transistor Q13 is connected to the C-pole of the third transistor Q21 via an inductor. The voltage is stepped down by controlling the on / off conditions of the transistors to obtain a 12V auxiliary power supply.
[0015] Specifically, a parallel diode group is connected between the B pole of the second transistor Q22, the E pole of the second transistor Q22, and the E pole of the fourth transistor Q13, and the E pole of the fourth transistor Q13 is connected to a voltage-stabilizing diode. When this circuit is working, when the voltage at the E pole of the first transistor is greater than the voltage at the B pole, the first transistor is turned on, a voltage difference exists between the upper and lower parts of the parallel diode group, the second transistor is turned on, the voltage at the B pole of the third transistor is 0, the third transistor is turned on, and the current is output to the outside after passing through the inductor. When the voltage rises to 12V, the fourth transistor and the voltage-stabilizing diode are turned on, and current forms a path after passing through the diode and the capacitor, pulling down the voltage at the B pole of the second transistor. At this time, the second transistor is turned off, and the third transistor is turned off. After that, the voltage drops below 12V and the cycle is repeated until the voltage is output stably.
[0016] Furthermore, refer again to Figure 1 The specific embodiment shown is described in detail. This is a battery-powered auxiliary power supply capable of controlling circuits, sensing circuits, and powering a cooling fan. This circuit implements a switching function by controlling the conduction of D13, Q9, Q21, Q22, R19, R85, and R221. Q21 is also controlled to conduct and shut off at intervals through Q13, ZD1, D25, C28, R30, and Q22, achieving voltage regulation. When a battery voltage is applied, and Ve of Q9 is greater than Vb, Q9 turns on. A voltage difference exists across D13, causing Q22 to turn on. When Vb of Q21 is equal to 0, Q21 turns on, and current flows through L4 for output. When the voltage rises to 12V, Q13 and ZD1 are turned on, creating a current path through D25 and C28 that lowers Vb at Q22. This causes Q22 to turn off, and Q21 to turn off. The voltage then drops below 12V, and the cycle repeats until the output voltage stabilizes.
[0017] The auxiliary power supply can provide a power supply to start the above circuits when the PV input is too low to start the control circuit and the sensing circuit.
[0018] In specific usage scenarios, after adopting the above solution, by adding a power auxiliary circuit, when the PV is insufficient, this circuit can be used to provide continuous current to the control circuit and the sensor circuit, so that they can operate normally, and the product can always remain in standby or charging (normal PV input). The display screen can also always read the various information and operating conditions of the machine without losing the stored information.
[0019] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.
Claims
1. An auxiliary power supply circuit, characterized in that: include: A first triode, a second triode, a third triode, and a fourth triode, wherein the C pole of the first triode is connected to the C pole of the second triode, the B pole of the third triode is connected to the C poles of the first triode and the second triode at the same time, and the B pole of the fourth triode is connected to the C pole of the third triode via an inductor; the voltage is reduced by controlling the on-off conditions of the triodes, thereby obtaining a 12V auxiliary power supply.
2. The circuit according to claim 1, wherein: A parallel diode group is connected between the B pole of the second transistor, the E pole of the second transistor, and the E pole of the fourth transistor, and the E pole of the fourth transistor is connected to a voltage-stabilizing diode. When this circuit is working, when the E pole voltage of the first transistor is greater than the B pole voltage, the first transistor is turned on, there is a voltage difference between the upper and lower parts of the parallel diode group, the second transistor is turned on, the B pole voltage of the third transistor is 0, the third transistor is turned on, and the current is output to the outside after passing through the inductor. When the voltage rises to 12V, the fourth transistor and the voltage-stabilizing diode are turned on, and current forms a path after passing through the diode and the capacitor, pulling down the B pole voltage of the second transistor. At this time, the second transistor is turned off, and the third transistor is turned off. After that, the voltage drops below 12V and the cycle is repeated until the voltage is output stably.