Isolation bus voltage sampling circuit

Abstract

The utility model belongs to the technical field of voltage sampling circuits, and particularly relates to an isolation bus voltage sampling circuit. Comprising a transformer T1 used for voltage conversion and electrical isolation, the primary side of the transformer T1 is provided with a rectifier bridge circuit and a switching power supply chip U1, the secondary side of the transformer T1 is provided with a secondary rectifier filter circuit, and the secondary rectifier filter circuit is provided with an output end VINDC used for voltage detection. And a bus voltage isolation sampling mode is adopted, so that the damage of components caused by unstable bus voltage is avoided, and the real-time monitoring of the bus voltage is ensured.

Description

Technical Field

[0001] This utility model belongs to the field of voltage sampling circuit technology, and particularly relates to an isolated bus voltage sampling circuit. Background Technology

[0002] In servo drives, it's necessary to sample the bus voltage. When the motor reverses, the back electromotive force (EMF) causes the bus voltage to rise, requiring the release of backflow energy. Simultaneously, the higher the motor speed, the higher the back EMF voltage during reverse rotation, necessitating the release of more energy. Furthermore, as the bus voltage increases, the phase current of the motor with the same duty cycle also increases, requiring a decrease in the PWM duty cycle to ensure normal motor operation. The voltage is increased accordingly to ensure proper motor function. By sampling the bus voltage, the motor's operating status can be monitored in real time, ensuring it operates within voltage limits and preventing motor damage or malfunctions due to excessively high or low voltage.

[0003] For example, a Chinese patent document discloses a linear optocoupler-based bus voltage sampling and detection system [2018200326423], which includes a voltage divider resistor A. AC power is electrically connected to the voltage divider resistor A, sampling resistor A, and bleeder resistor via a rectifier bridge A, forming a closed loop through a bleeder switch B. A bus capacitor is connected in parallel on this loop. Both the voltage divider resistor A and the sampling resistor A are connected to a comparator A. The comparator A is electrically connected to the output terminal or comparator B via the bleeder switch A. The comparator B is interconnected with the sampling resistor B, the voltage divider resistor B, and the rectifier bridge B. This invention replaces the original voltage sensor with a linear optocoupler and adds the judgment of the bleeder point voltage, i.e., judging the cause of the bus voltage rise to determine whether to bleed. This effectively avoids the influence of the heat generated by the voltage divider resistor, ensuring that the bus voltage is always accurately monitored, thus protecting the servo drive.

[0004] The above technical solution solves the technical problem of bus voltage sampling and detection. However, in the above technical solution, when the bus voltage is too low, the input current required to output the same power is larger, which may damage the rectifier bridge. When the bus voltage is too high, it may exceed the withstand voltage of the bus capacitor, rectifier bridge and other devices, causing damage to the devices. Utility Model Content

[0005] The purpose of this invention is to address the above-mentioned problems by providing an isolation bus voltage sampling circuit to realize a high-voltage isolation protection detection circuit.

[0006] To achieve the above objectives, this utility model adopts the following technical solution: an isolation bus voltage sampling circuit, including a transformer T1 for voltage transformation and electrical isolation, wherein a rectifier bridge circuit is provided on the primary side of the transformer T1. open Power-off chip U1, the secondary side of the transformer T1 is provided with a secondary rectifier and filter circuit, and the secondary rectifier and filter circuit is provided with an output terminal VIN_DC for voltage checking.

[0007] In the aforementioned isolated bus voltage sampling circuit, the rectifier bridge circuit includes four diodes: a first diode D1, a second diode D2, a third diode D3, and a fourth diode D4. The rectifier bridge circuit is electrically connected to the bus.

[0008] In the aforementioned isolated bus voltage sampling circuit, the four diodes—first diode D1, second diode D2, third diode D3, and fourth diode D4—are connected in a bridge configuration to form a rectifier bridge, utilizing the unidirectional conductivity of diodes.

[0009] In the aforementioned isolated bus voltage sampling circuit, the rectifier circuit and Switching power supply chip U1 is connected in series,

[0010] In the aforementioned isolated bus voltage sampling circuit, a first capacitor C1 is connected in parallel with the rectifier circuit.

[0011] In the aforementioned isolated bus voltage sampling circuit, the secondary rectifier filter circuit includes a fifth diode D5 and a sixth diode D6. The anode of the fifth diode D5 is connected to one end of the secondary winding of transformer T1, and the anode of the sixth diode D6 is connected to the other end of the secondary winding of transformer T1. The cathode of the sixth diode D6 is connected to the cathode of the fifth diode D5, and the common node of the cathodes of the fifth diode D5 and the sixth diode D6 is grounded.

[0012] In the aforementioned isolated bus voltage sampling circuit, the secondary rectifier filter circuit further includes a second capacitor C2, a third capacitor C3, and a fourth capacitor C4. The second capacitor C2 is connected between the common cathode node of the fifth diode D5 and the sixth diode D6 and the fifth diode D5.

[0013] The third capacitor C3 is connected between the common node of the cathodes of the fifth diode D5 and the sixth diode D6 and the sixth diode D6.

[0014] In the aforementioned isolated bus voltage sampling circuit, the secondary rectifier filter circuit further includes a first resistor R1 and a second resistor R2. The first resistor R1 and the second resistor R2 are connected in series, with one end connected between the sixth diode D6 and the third capacitor C3, and the other end connected to the common cathode node of the fifth diode D5 and the sixth diode D6.

[0015] In the aforementioned isolated bus voltage sampling circuit, the secondary rectifier and filter circuit further includes... Magnetic beads L1, as described Magnetic beads One end of L1 is connected between the first resistor R1 and the second resistor R2.

[0016] In the aforementioned isolated bus voltage sampling circuit, the other end is the output terminal VIN_DC, the fourth... capacitance One end of C4 is connected between the first resistor R1 and the second resistor R2, and the other end is grounded.

[0017] Compared with existing technologies, the advantages of this utility model are as follows:

[0018] 1. Bus voltage isolation sampling, It achieves isolation between high-voltage and low-voltage electricity. . Electricity was achieved through an electro-magnetic-electric approach. Gas isolation. Cuts off the propagation path of "ground" interference, effectively suppressing spike pulses and various noise interferences, and improving the system's electromagnetic compatibility. Tolerance.

[0019] 2. Filter out interference caused by the driver operation and improve the bus voltage sampling accuracy. Attached Figure Description

[0020] Figure 1 This is the circuit schematic diagram provided by this utility model.

[0021] In the diagram, there is a rectifier bridge circuit 1, a secondary rectifier and filter circuit 2, and a transformer T1. Switching power supply chip The output terminals of U1 include: first diode D1, second diode D2, third diode D3, fourth diode D4, fifth diode D5, sixth diode D6; first capacitor C1, second capacitor C2, third capacitor C3, fourth capacitor C4; first resistor R1; and second resistor R2. Magnetic beads L1. Detailed Implementation

[0022] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0023] Includes a transformer T1 for voltage transformation and electrical isolation, wherein a rectifier bridge circuit 1 is provided on the primary side of the transformer T1. Switching power supply chip U1, the secondary side of the transformer T1 is provided with a secondary rectifier and filter circuit 2, and the secondary rectifier and filter circuit 2 is provided with an output terminal VIN_DC for voltage checking.

[0024] During servo power-on, when the bus voltage reaches 130V Switching power supply chip U1 starts working upon startup. Switching power supply. chip After U1 is started, the internal switching transistors begin to work. The rectifier bridge circuit converts the input high-voltage AC power into DC power. The transformer T1 transforms the rectified voltage to achieve high-voltage isolation, while storing energy on the primary side.

[0025] When the internal switching transistor of the switching power supply U1 is turned off, the inductor on the primary side of transformer T1 begins to release energy, and voltage output begins on the secondary side of transformer T1; that is, utilizing the flyback switching power supply operating mode, the secondary voltage of transformer T1 has been established. The isolation bus detection of transformer T1 selects a negative voltage. Output diode D6 reverse soldering It forms a forward converter with the primary winding of transformer T1. This causes the output voltage VIN_DC to follow the fluctuations of the bus voltage. When there is voltage on the primary side, the bus voltage sampling coil will output a voltage. The ARM can detect the current bus voltage through the VIN_DC signal at its output terminal.

[0026] Specifically, the rectifier bridge circuit 1 includes four diodes: a first diode D1, a second diode D2, a third diode D3, and a fourth diode D4. The rectifier bridge circuit 1 is electrically connected to the bus. These four diodes, D1, D2, D3, and D4, utilize the unidirectional conductivity of diodes to form a rectifier bridge in a bridge configuration. The unidirectional conductivity of the diodes is used to convert alternating current (AC) to direct current (DC). Those skilled in the art can use different types of diodes to build the rectifier bridge, such as a common diode rectifier bridge, a fast recovery diode rectifier bridge, or a Schottky diode rectifier bridge. An integrated rectifier module can also be used instead. Selecting a rectifier bridge circuit on the primary side of transformer T1 reduces energy loss and improves circuit stability and reliability.

[0027] The rectifier circuit 1 and Switching power supply chip U1 is connected in series to control the operating state of the primary side of transformer T1. In this embodiment, the... Internal components of the switching power supply chip The transistor is a MOSFET switch, but those skilled in the art can also use bipolar transistors, junction field-effect transistors, etc. as substitutes.

[0028] Preferably, a first capacitor C1 is connected in parallel with the output terminals of the rectifier circuit 1 to smooth the DC voltage at the rectified end. Its capacitance is selected based on the output power and ripple requirements of the power supply circuit.

[0029] Preferably, the secondary rectifier filter circuit 2 includes a fifth diode D5 and a sixth diode D6. The anode of the fifth diode D5 is connected to one end of the secondary winding of the transformer T1 to form a flyback topology. The transformer T1 stores energy when the switching power supply chip U1 is turned on and releases energy to the subsequent stage after the switching power supply chip U1 is turned off, so that the current can flow to the subsequent electrical circuit through the fifth diode D5 when the switching power supply U1 is turned off.

[0030] The anode of the sixth diode D6 is connected to the other end of the secondary winding of the transformer T1, and the cathode is connected to the cathode of the fifth diode D5 to form a forward converter. When the switching power supply chip U1 is turned on, the transformer T1 delivers the bus voltage to the secondary side in a proportional manner. The current flows through the sixth diode D6 to the subsequent stage and forms a stable voltage through the capacitor C3.

[0031] The common node of the cathodes of the fifth diode D5 and the sixth diode D6 is grounded. Grounding plays a crucial role in establishing a current loop and ensuring correct signal conversion and processing. It also provides a stable reference potential, allowing voltage signals in the circuit to be transmitted and processed under a defined potential reference, which helps improve the stability and reliability of the circuit and reduces signal drift and interference.

[0032] Furthermore, the secondary rectifier and filter circuit 2 also includes a second capacitor C2, a third capacitor C3, and a fourth capacitor C4. The second capacitor C2 is connected between the common cathode node of the fifth diode D5 and the sixth diode D6 and the fifth diode D5; that is, it is connected to the output terminal of the pulsating DC voltage after rectification by the fifth diode D5 and the sixth diode D6, with the other end grounded. Its main function is to perform initial filtering on the rectified pulsating DC voltage, smoothing the voltage waveform and reducing voltage ripple.

[0033] The third capacitor C3 is connected between the common cathode node of the fifth diode D5 and the sixth diode D6 and the sixth diode D6. Similar to the second capacitor C2, one end is connected to the circuit node after the common cathode node of the fifth diode D5 and the sixth diode D6, and the other end is grounded. The output bus sampling voltage is filtered by the third capacitor C3, making the output bus sampling voltage more stable.

[0034] Furthermore, the secondary rectifier and filter circuit 2 also includes a first resistor R1 and a second resistor R2. One end of the first resistor R1 and the second resistor R2 are connected in series between the sixth diode D6 and the third capacitor C3, and the other end is connected to the common cathode node of the fifth diode D5 and the sixth diode D6. The first resistor R1 and the second resistor R2 together form a voltage divider circuit to sample the output DC voltage, limiting the voltage on the bus voltage sampling circuit within the MCU's ADC sampling range, while simultaneously providing a signal related to the output voltage. The second resistor R2 and the first resistor R1 together determine the voltage division ratio, converting the output voltage into a sampled voltage according to a certain ratio, so as to feed it back to the control circuit and achieve stable control of the output voltage.

[0035] Furthermore, the secondary rectifier filter circuit 2 also includes a ferrite bead L1. One end of the ferrite bead L1 is connected between the first resistor R1 and the second resistor R2, and the other end is the output terminal VIN_DC. In the filter circuit, the inductor L1, the second capacitor C2, and the third capacitor C3 together form an LC filter circuit. The ferrite bead is used to filter out high-frequency interference and further filter out residual ripple in the DC voltage, making the output DC voltage smoother and more stable, and providing a high-quality DC sampling signal.

[0036] The fourth capacitor C4 is connected at one end between the first resistor R1 and the second resistor R2, and at the other end to ground. Together with the first resistor R1 and the second resistor R2, it forms part of the sampling circuit, used to stabilize the voltage at the sampling point and also to filter the sampling signal, further improving the accuracy of the sampling voltage.

[0037] The specific embodiments described herein are merely illustrative examples illustrating the spirit of this utility model. Those skilled in the art to which this utility model pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of this utility model or exceeding the scope defined by the appended claims.

[0038] Although this paper frequently uses terms such as rectifier bridge circuit 1, secondary rectifier filter circuit 2, transformer T1, first diode D1, second diode D2, third diode D3, fourth diode D4, fifth diode D5, sixth diode D6, first capacitor C1, second capacitor C2, third capacitor C3, fourth capacitor C4, first resistor R1, second resistor R2, and ferrite bead L1, the possibility of using other terms is not excluded. These terms are used merely for the convenience of describing and explaining the essence of this utility model; interpreting them as any additional limitation would contradict the spirit of this utility model.

Claims

1. An isolated bus voltage sampling circuit, characterized in that, The transformer T1 is used for voltage transformation and electrical isolation. The primary side of the transformer T1 is provided with a rectifier bridge circuit (1) and a switching power supply chip U1. The secondary side of the transformer T1 is provided with a secondary rectifier filter circuit (2). The secondary rectifier filter circuit (2) is provided with an output terminal VIN_DC for voltage checking.

2. The isolated bus voltage sampling circuit according to claim 1, characterized in that, The rectifier bridge circuit (1) includes four diodes: a first diode D1, a second diode D2, a third diode D3, and a fourth diode D4. The rectifier bridge circuit (1) is electrically connected to the bus.

3. The isolated bus voltage sampling circuit according to claim 2, characterized in that, The four diodes, namely the first diode D1, the second diode D2, the third diode D3, and the fourth diode D4, are connected in a bridge configuration to form a rectifier bridge, utilizing the unidirectional conductivity of diodes.

4. The isolated bus voltage sampling circuit according to claim 3, characterized in that, The rectifier circuit (1) is connected in series with the switching power supply chip U1.

5. The isolated bus voltage sampling circuit according to claim 3, characterized in that, The rectifier circuit (1) is connected in parallel with a first capacitor C1.

6. The isolated bus voltage sampling circuit according to claim 1, characterized in that, The secondary rectifier filter circuit (2) includes a fifth diode D5 and a sixth diode D6. The anode of the fifth diode D5 is connected to one end of the secondary winding of the transformer T1, and the anode of the sixth diode D6 is connected to the other end of the secondary winding of the transformer T1. The cathode is connected to the cathode of the fifth diode D5, and the common node of the cathodes of the fifth diode D5 and the sixth diode D6 is grounded.

7. The isolated bus voltage sampling circuit according to claim 6, characterized in that, The secondary rectifier filter circuit (2) further includes a second capacitor C2, a third capacitor C3, and a fourth capacitor C4. The second capacitor C2 is connected between the common cathode node of the fifth diode D5 and the sixth diode D6 and the fifth diode D5. The third capacitor C3 is connected between the common node of the cathodes of the fifth diode D5 and the sixth diode D6 and the sixth diode D6.

8. The isolated bus voltage sampling circuit according to claim 7, characterized in that, The secondary rectifier filter circuit (2) further includes a first resistor R1 and a second resistor R2. The first resistor R1 and the second resistor R2 are connected in series, with one end connected between the sixth diode D6 and the third capacitor C3, and the other end connected to the common cathode node of the fifth diode D5 and the sixth diode D6.

9. The isolated bus voltage sampling circuit according to claim 8, characterized in that, The secondary rectifier filter circuit (2) further includes a ferrite bead L1, one end of which is connected between the first resistor R1 and the second resistor R2, and the other end is the output terminal VIN_DC.

10. The isolated bus voltage sampling circuit according to claim 8, characterized in that... The fourth capacitor C4 is connected at one end between the first resistor R1 and the second resistor R2, and at the other end is grounded.

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