High-frequency switching power supply output loop dynamic dummy load circuit

Abstract

The utility model discloses a dynamic dummy load circuit of an output loop of a high-frequency switching power supply, which belongs to the technical field of switching power supply circuits and comprises a dummy load circuit, a voltage detection circuit, a current detection circuit, a full-wave rectification circuit, an L-shaped filter circuit and a single chip microcomputer. The dummy load circuit, the voltage detection circuit, the full-wave rectification circuit and the L-type filter circuit are sequentially arranged at the output end of the high-frequency switching power supply in parallel; the input end of the current detection circuit is connected with the output end of the L-shaped filter circuit; the single-chip microcomputer is respectively connected with the dummy load circuit, the current detection circuit and the voltage detection circuit. According to the utility model, through the cooperation of the single-chip microcomputer, the current detection circuit and the voltage detection circuit, the connection and disconnection of the dummy load circuit are dynamically and automatically controlled in real time according to the working state of the power supply of the power supply module, the overall efficiency of the output power and the input power of the power supply module can be effectively improved, and the heat generated during the operation of the power supply module is reduced.

Description

Technical Field

[0001] This utility model belongs to the technical field of switching power supply circuits, specifically relating to a dynamic dummy load circuit for the output circuit of a high-frequency switching power supply. Background Technology

[0002] The power supply module is characterized by high output voltage and high output power, with a normal output voltage of 300Vdc and an output power exceeding 6 kilowatts. With the development of switching power supply technology, high-voltage, high-power power supply modules all employ microcontroller-based digital control (DSP). During operation, when the power output port of the high-power power supply module experiences no-load or light-load conditions, the power control circuit cannot detect the output current signal, and the PWM signal (pulse width modulation signal) emitted by the microcontroller in the power control chip is in waveform generation mode. The power supply module may exhibit the following operating conditions:

[0003] 1. If the switching frequency of the PWM signal of the power supply module is lower than 20KHz, the power supply module will produce an audio whistling sound;

[0004] 2. The output voltage of the power module may become unstable, and the output voltage of the power module may be higher than the originally set output voltage.

[0005] When high-power power modules are in operation, if the power output port experiences no-load or light-load conditions, existing technologies address these issues by adding a dummy load (also called a dead load) to the power module's output port. Adding a dummy load to the power module's output port can bring the power module into a normal operating state. However, adding a dummy load to the power module's output port has the following drawbacks:

[0006] 1. The overall efficiency of the power module's output and input power decreases;

[0007] 2. The power module has an additional heat source during operation. Utility Model Content

[0008] The purpose of this invention is to address the aforementioned shortcomings in the prior art by providing a dynamic dummy load circuit for the output circuit of a high-frequency switching power supply, thereby solving the problems of power reduction and increased heat generation when adding a dummy load to the output port of the existing power module.

[0009] To achieve the above objectives, the technical solution adopted by this utility model is as follows:

[0010] A dynamic dummy load circuit for the output circuit of a high-frequency switching power supply includes a dummy load circuit, a voltage detection circuit, a current detection circuit, a full-wave rectifier circuit, an L-type filter circuit, and a microcontroller.

[0011] The dummy load circuit, voltage detection circuit, full-wave rectifier circuit, and L-type filter circuit are connected in parallel at the output of the high-frequency switching power supply; the input of the current detection circuit is connected to the output of the L-type filter circuit; and the microcontroller is connected to the dummy load circuit, current detection circuit, and voltage detection circuit respectively.

[0012] Furthermore, the dummy load circuit includes resistors R89, R96, R104, R158, R68, R71, and a switching MOSFET Q5; resistors R89 and R104 are connected in parallel, and resistors R158 and R96 are connected in parallel.

[0013] The parallel resistors R89 and R104 are connected to the input terminals of the parallel resistors R158 and R96; the output terminals of the parallel resistors R158 and R96 are connected to the drain of the switching MOSFET Q5, and the gate of the switching MOSFET Q5 is connected to the resistors R68 and R71 respectively.

[0014] Furthermore, the input terminal of the resistor R68 is connected to the PMW9 port of the microcontroller.

[0015] Furthermore, the voltage detection circuit includes resistors R65, R62, R61, R67, and R75 connected in series; resistors R67 and R75 are connected to the V_FEED1 port of the microcontroller.

[0016] Furthermore, the full-wave rectifier circuit includes fast recovery diodes D60, D61, D62, and D63; fast recovery diodes D60 and D63 are connected in series, and fast recovery diodes D61 and D62 are connected in series; the series-connected fast recovery diodes D60 and D63 are connected in parallel with the series-connected fast recovery diodes D61 and D62.

[0017] Furthermore, the L-shaped filter circuit includes capacitor C91, capacitor C92, and inductor L12; capacitor C92, capacitor C91, and inductor L12 are connected in parallel at the output terminal of the high-frequency switching power supply; the input terminal of inductor L12 is connected to the output terminal of the full-wave rectifier circuit.

[0018] Furthermore, the current detection circuit is located between the output terminals of capacitor C91 and capacitor C92.

[0019] Furthermore, the current detection circuit includes shunt RD1, shunt RD2, shunt RD3 and shunt RD4; shunt RD4, shunt RD3, shunt RD2 and shunt RD1 are connected in parallel in sequence; shunt RD1 is connected in parallel with resistor R72 and capacitor C24 which are connected in series.

[0020] Furthermore, a microcontroller's CFC port is connected between the resistor R72 and the capacitor C24.

[0021] The dynamic dummy load circuit for the output circuit of the high-frequency switching power supply provided by this utility model has the following beneficial effects:

[0022] This circuit can be applied to high-voltage output high-power power module circuits. When the power module's output port experiences no-load or light-load conditions, the DSP microcontroller, through a current detection circuit, detects a sampled current signal less than a set value. The DSP microcontroller then sends a 15V voltage signal to the gate of the switching MOSFET, turning it on. This activates the dummy load circuit in the power output loop, allowing the power module's input and output to operate normally. When the power module is operating normally (without no-load or light-load conditions), the DSP microcontroller, through the power module's output current detection circuit, detects a sampled current signal that is within the normal set value. The DSP microcontroller then sends a low-voltage signal to the gate of the switching MOSFET, deactivating it and disconnecting the dummy load circuit from the power output loop.

[0023] 2. This utility model, through the cooperation of a microcontroller, a current detection circuit, and a voltage detection circuit, dynamically and automatically controls the connection and disconnection of the dummy load circuit in real time according to the working status of the power supply module. This can effectively improve the overall efficiency of the power supply module's output power and input power, while also reducing the heat generated during the operation of the power supply module.

[0024] 3. The circuit design of this utility model reduces circuit complexity, ensures reliable operation, and provides flexible application, greatly improving the performance of high-frequency switching power supplies. Attached Figure Description

[0025] Figure 1 This is a circuit diagram of the dynamic dummy load circuit for the output circuit of the high-frequency switching power supply of the present invention. Detailed Implementation

[0026] The specific embodiments of this utility model are described below to enable those skilled in the art to understand this utility model. However, it should be understood that this utility model is not limited to the scope of the specific embodiments. For those skilled in the art, as long as various changes are within the spirit and scope of this utility model as defined and determined by the appended claims, these changes are obvious. All utility model creations utilizing the concept of this utility model are within the scope of protection.

[0027] Example 1

[0028] This embodiment provides a dynamic dummy load circuit for the output circuit of a high-frequency switching power supply. It is applicable to three-phase input power modules of high-frequency switching power supplies with an output power of 6000W or higher, an operating voltage range of 323–475Vac, and an output voltage of 300V / 20A. This circuit effectively improves the overall efficiency of the power module's output and input power while reducing heat generation during operation. (Reference) Figure 1 Specifically, it includes:

[0029] The circuit consists of a dummy load circuit, a voltage detection circuit, a current detection circuit, a full-wave rectifier circuit, an L-type filter circuit, and a microcontroller.

[0030] In this embodiment, the dummy load circuit, voltage detection circuit, full-wave rectifier circuit, and L-type filter circuit are connected in parallel at the output terminal of the high-frequency switching power supply. The input terminal of the current detection circuit is connected to the output terminal of the L-type filter circuit. The microcontroller is connected to the dummy load circuit, the current detection circuit, and the voltage detection circuit, respectively.

[0031] To achieve dynamic control of the dummy load circuit, this embodiment preferably uses a DSP microcontroller, which is connected to the current detection circuit to receive the power module output current collected by the current detection circuit in real time, and outputs a corresponding voltage signal based on the output current to control the dummy load circuit; at the same time, the DSP microcontroller also receives the power module output current collected by the voltage detection circuit in real time.

[0032] To address the issues of no-load and light-load at the output port of the power module, this embodiment includes a dummy load circuit at the output port of the power module. As a preferred embodiment, the dummy load circuit includes resistors R89, R96, R104, R158, R68, R71, and a switching MOSFET Q5.

[0033] Among them, resistors R89 and R104 are connected in parallel, and resistors R158 and R96 are connected in parallel;

[0034] The parallel resistors R89 and R104 are connected to the input terminals of the parallel resistors R158 and R96; the output terminals of the parallel resistors R158 and R96 are connected to the drain of the switching MOSFET Q5; the gate of the switching MOSFET Q5 is connected to resistors R68 and R71 respectively; the input terminal of resistor R68 is connected to the PMW9 signal port of the microcontroller.

[0035] In actual operation, the switching MOSFET is controlled by the DSP microcontroller. When the switching MOSFET is turned on, it connects the resistors R89, R96, R104, and R158 in the dummy load circuit to the output port of the power module. When the switching MOSFET is turned off, it disconnects from the output port of the power module.

[0036] To achieve real-time detection of the output port voltage of the power module, this embodiment preferably includes a voltage detection circuit comprising resistors R65, R62, R61, R67, and R75 connected in series. Among them, resistors R67 and R75 are connected to the V_FEED1 port of the microcontroller to transmit the detected voltage information to the DSP microcontroller.

[0037] The full-wave rectifier circuit is used to convert alternating current into direct current. In this embodiment, the preferred full-wave rectifier circuit includes fast recovery diodes D60, D61, D62, and D63.

[0038] Among them, fast recovery diodes D60 and D63 are connected in series, and fast recovery diodes D61 and D62 are connected in series; the fast recovery diodes D60 and D63 connected in series are connected in parallel with the fast recovery diodes D61 and D62 connected in series.

[0039] The L-type filter circuit is used to filter out high-frequency noise and ripple, ensuring the stability and purity of the output power supply. In this embodiment, the preferred L-type filter circuit includes capacitor C91, capacitor C92 and inductor L12; capacitor C92, capacitor C91 and inductor L12 are connected in parallel in sequence at the output terminal of the high-frequency switching power supply; the input terminal of inductor L12 is connected to the output terminal of the full-wave rectifier circuit.

[0040] In this embodiment, the current detection circuit is located between capacitor C91 and capacitor C92;

[0041] Specifically, the current detection circuit includes shunts RD1, RD2, RD3, and RD4; shunts RD4, RD3, RD2, and RD1 are connected in parallel in sequence; shunt RD1 is connected in parallel with resistor R72 and capacitor C24, which are connected in series; a CFC port of the microcontroller is connected between resistor R72 and capacitor C24, through which the current detection circuit transmits the detected current information to the DSP microcontroller in real time.

[0042] The working principle of the dynamic dummy load circuit in the output circuit of the high-frequency switching power supply in this embodiment is as follows:

[0043] When the power supply module is running normally (without no load or light load at the output), the current detection circuit sends a normal setting signal (CFC) to the DSP microcontroller for processing. The DSP microcontroller judges it as a normal signal and then sends a low-level signal (PWM9) to the gate of the switching MOSFET Q5. The switching MOSFET Q5 is not turned on, and the resistors R89, R96, R104, and R158 in the dummy load circuit are disconnected from the circuit.

[0044] When the power output port of the power module experiences no-load or light-load conditions, the DSP microcontroller receives the current signal transmitted by the current detection circuit. If the detected sampled current signal (CFC) is less than the current signal set value, the DSP microcontroller determines it to be an abnormal signal and then sends a 15V level signal (PWM9) to the gate of the switching MOSFET Q5. The switching MOSFET Q5 is turned on, and the resistors R89, R96, R104, and R158 in the dummy load circuit are connected to the circuit to operate, and the power module's output and input operate normally.

[0045] This invention can improve the overall efficiency of the power module's output power and input power, while reducing the heat generated during operation. The entire circuit design is simple, reliable, and flexible, greatly improving the performance of high-frequency switching power supplies.

[0046] Although the specific embodiments of the utility model have been described in detail with reference to the accompanying drawings, this should not be construed as limiting the scope of protection of this patent. Various modifications and variations that can be made by those skilled in the art without inventive effort within the scope described in the claims still fall within the scope of protection of this patent.

Claims

1. A dynamic dummy load circuit for the output circuit of a high-frequency switching power supply, wherein the dynamic dummy load circuit is connected to the output terminal of the high-frequency switching power supply, characterized in that: It includes a dummy load circuit, a voltage detection circuit, a current detection circuit, a full-wave rectifier circuit, an L-type filter circuit, and a microcontroller; The dummy load circuit, voltage detection circuit, full-wave rectifier circuit, and L-type filter circuit are connected in parallel at the output of the high-frequency switching power supply; the input of the current detection circuit is connected to the output of the L-type filter circuit; and the microcontroller is connected to the dummy load circuit, current detection circuit, and voltage detection circuit respectively.

2. The dynamic dummy load circuit for the output circuit of the high-frequency switching power supply according to claim 1, characterized in that: The dummy load circuit includes resistors R89, R96, R104, R158, R68, R71, and a switching MOSFET Q5; resistors R89 and R104 are connected in parallel, and resistors R158 and R96 are connected in parallel. The parallel resistors R89 and R104 are connected to the input terminals of the parallel resistors R158 and R96; the output terminals of the parallel resistors R158 and R96 are connected to the drain of the switching MOSFET Q5, and the gate of the switching MOSFET Q5 is connected to the resistors R68 and R71 respectively.

3. The dynamic dummy load circuit for the output circuit of the high-frequency switching power supply according to claim 2, characterized in that: The input terminal of the resistor R68 is connected to the PMW9 port of the microcontroller.

4. The dynamic dummy load circuit for the output circuit of the high-frequency switching power supply according to claim 1, characterized in that: The voltage detection circuit includes resistors R65, R62, R61, R67, and R75 connected in series; resistors R67 and R75 are connected to the V_FEED1 port of the microcontroller.

5. The dynamic dummy load circuit for the output circuit of the high-frequency switching power supply according to claim 1, characterized in that: The full-wave rectifier circuit includes fast recovery diodes D60, D61, D62, and D63; fast recovery diodes D60 and D63 are connected in series, and fast recovery diodes D61 and D62 are connected in series; the series-connected fast recovery diodes D60 and D63 are connected in parallel with the series-connected fast recovery diodes D61 and D62.

6. The dynamic dummy load circuit for the output circuit of the high-frequency switching power supply according to claim 5, characterized in that: The L-shaped filter circuit includes capacitor C91, capacitor C92, and inductor L12; capacitor C92, capacitor C91, and inductor L12 are connected in parallel at the output terminal of the high-frequency switching power supply; the input terminal of inductor L12 is connected to the output terminal of the full-wave rectifier circuit.

7. The dynamic dummy load circuit for the output circuit of the high-frequency switching power supply according to claim 6, characterized in that: The current detection circuit is located between the output terminals of capacitor C91 and capacitor C92.

8. The dynamic dummy load circuit for the output circuit of the high-frequency switching power supply according to claim 7, characterized in that: The current detection circuit includes shunt RD1, shunt RD2, shunt RD3 and shunt RD4; shunt RD4, shunt RD3, shunt RD2 and shunt RD1 are connected in parallel in sequence; shunt RD1 is connected in parallel with resistor R72 and capacitor C24 which are connected in series.

9. The dynamic dummy load circuit for the output circuit of the high-frequency switching power supply according to claim 8, characterized in that: The CFC port of the microcontroller is connected between the resistor R72 and the capacitor C24.

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