Open-phase detection device and servo driver for multi-phase alternating current power supply

Abstract

The utility model relates to an open-phase detection device for a multi-phase AC power supply and a servo driver. The apparatus includes: a plurality of input pins; at least two optical couplers, each optical coupler comprising a primary side and a secondary side, the primary side of each optical coupler being arranged between two input pins of the plurality of input pins so as to emit a corresponding optical signal based on a voltage difference between the two input pins, the secondary sides of the optical couplers are electrically connected with each other in parallel and are configured to output corresponding electric signals according to the optical signals emitted by the respective corresponding primary sides; and the output unit is connected to the secondary sides of the at least two optical couplers and is configured to output a detection result of the open-phase detection device based on the electric signals provided by the secondary sides. The device has the advantages that the use of an external high-voltage rectifier bridge and a voltage stabilizing diode can be avoided, the circuit structure is simplified, and the accuracy and the reliability of an open-phase detection result are improved.

Description

Technical Field

[0001] The utility model relates to the field of power supply detection, and more specifically, to a phase loss detection device for a multi-phase AC power supply, and a servo driver comprising the phase loss detection device. Background Art

[0002] In industrial control systems, multi-phase (usually three-phase) AC power is the most common power supply method. In a three-phase AC power supply, due to the interdependence between its three phases, if a phase loss occurs (i.e. one or several phases lose power, also known as "phase loss"), it may cause instability of the entire system or even cause system failure. Therefore, detecting phase loss in a three-phase AC power supply is crucial to ensure the stable operation of the power system.

[0003] In the traditional AC power phase loss detection scheme, a detection circuit composed of a high-voltage rectifier bridge, a current limiting resistor, a Zener diode, and a DC photocoupler is usually used to identify the phase loss fault of the power supply. Alternatively, the power bus voltage waveform under load can be collected through software control and the power phase loss can be determined through software calculation. Although both schemes can detect the loss of power phase, there are some shortcomings, such as complex circuit design, high cost, and insufficient reliability. In addition, when the system has both DC and AC connections, the traditional detection scheme may no longer be applicable. Utility Model Content

[0004] The utility model aims to solve the deficiencies in the existing AC power phase loss detection scheme, improves the traditional phase loss detection circuit design, and provides a phase loss detection device for multi-phase AC power with simple structure, low cost and high reliability.

[0005] The first aspect of the utility model provides a phase loss detection device for a multi-phase AC power supply. According to an optional embodiment, the phase loss detection device includes:

[0006] A plurality of input pins, each input pin being electrically connected to a corresponding one phase of the multi-phase AC power source;

[0007] at least two optical couplers, each optical coupler comprising a primary side and a secondary side, the primary side of each optical coupler being disposed between two input pins of the plurality of input pins to transmit a corresponding optical signal based on a voltage difference between the two input pins, and the secondary sides of the respective optical couplers being electrically connected to each other in parallel and configured to output a corresponding electrical signal according to the optical signal transmitted by the respective corresponding primary side; and

[0008] An output unit is connected to the secondary sides of the at least two optical couplers and is configured to output a detection result of the phase loss detection device based on the electrical signal provided by each secondary side.

[0009] According to an optional embodiment, the at least two optical couplers are AC optical couplers, and the primary side of each AC optical coupler includes a photodiode and another diode connected in reverse parallel to the photodiode.

[0010] According to an optional embodiment, the multi-phase AC power supply is a three-phase power supply, and the phase loss detection device includes three input pins and two optocouplers, wherein the first optocoupler is arranged between the first input pin and the second input pin, and the second optocoupler is arranged between the second input pin and the third input pin.

[0011] According to an optional embodiment, the phase loss detection device further includes a current limiting circuit, which is arranged between the multiple input pins and the at least two optocouplers, and is configured to limit the power supply signals output by the multiple input pins and provide them to the at least two optocouplers respectively.

[0012] According to an optional embodiment, the phase loss detection device further includes three current limiting resistors, wherein a first current limiting resistor is connected between the first input pin and the first input end of the first optocoupler, a second current limiting resistor is connected between the second input pin and the second input end of the first optocoupler, the first input end of the second optocoupler is connected to the second input end of the first optocoupler, and a third current limiting resistor is connected between the third input pin and the second input end of the second optocoupler.

[0013] According to an optional embodiment, the phase loss detection device further includes two voltage-dividing resistors, wherein the first voltage-dividing resistor is connected between the first input terminal and the second input terminal of the first optical coupler, and the second voltage-dividing resistor is connected between the first input terminal and the second input terminal of the second optical coupler.

[0014] According to an optional embodiment, the resistance values ​​of the three current-limiting resistors and the two voltage-dividing resistors are set according to the power supply voltage of the three-phase power supply and the required current of the first optocoupler and the second optocoupler.

[0015] According to an optional embodiment, the secondary side of each optocoupler includes a phototransistor, and the output unit includes a DC source and a pull-up resistor directly electrically connected to the DC source, wherein the collector of the phototransistor is connected to the pull-up resistor, and the emitter of the phototransistor is grounded.

[0016] According to an optional embodiment, the secondary side of each optocoupler includes a phototransistor, and the output unit includes a DC source and a pull-down resistor, wherein the collector of the phototransistor is connected to the DC source, and the emitter of the phototransistor is connected to the pull-down resistor.

[0017] The second aspect of the utility model further provides a servo driver, the servo driver comprising:

[0018] A phase loss detection device as described above;

[0019] A control chip is connected to the output unit of the phase loss detection device and is configured to interrupt the operation of the servo motor when receiving a phase loss indication signal from the output unit.

[0020] According to the phase loss detection device of the utility model, it adopts the configuration structure of two AC photocouplers, avoiding the use of external high-voltage rectifier bridges and voltage regulator diodes, which not only simplifies the circuit structure, but also reduces the total cost and volume of the circuit. In addition, the phase loss detection device focuses on the monitoring of multi-phase AC power supply, and can effectively detect during the power-on of electrical equipment and motor energy feedback. Even if there is an external input filter, it can quickly and accurately detect the input power supply status, thereby improving the accuracy and reliability of the phase loss detection result, and can adapt to various application scenarios of power supply phase loss detection (for example, AC and DC mixed connection). BRIEF DESCRIPTION OF THE DRAWINGS

[0021] By incorporating the accompanying drawings and Figure 1 With reference to the specific implementation modes used to illustrate certain principles of the present invention, other features and advantages of the method of the present invention will become clear or be described in more detail.

[0022] Figure 1 A circuit diagram of a phase loss detection device for a multi-phase AC power supply according to a first exemplary embodiment of the present utility model is shown.

[0023] Figure 2 A circuit diagram of a phase loss detection device for a multi-phase AC power supply according to a second exemplary embodiment of the present utility model is shown.

[0024] Figure 3 Shows Figure 1 Output simulation results of the phase loss detection device in . DETAILED DESCRIPTION

[0025] The following will describe the phase loss detection device for a multi-phase AC power supply according to the utility model with reference to the accompanying drawings and by way of example. In the following description, many specific details are set forth so that a person skilled in the art can more fully understand the utility model. However, it is obvious to a person skilled in the art that the implementation of the utility model may not have some of these specific details. On the contrary, it may be considered to implement the utility model with any combination of the following features and elements, regardless of whether they relate to different embodiments. Therefore, the following various aspects, features, embodiments and advantages are for illustrative purposes only and should not be regarded as elements or limitations of the claims.

[0026] In an ideal three-phase power system, the three-phase voltage and current are equal and the phase difference is 120 degrees under normal circumstances. However, in practical applications, due to power supply line failure, load imbalance, protection device action or internal equipment failure, one or more phases in the system may lose power or be underpowered. This phenomenon is called phase loss. Phase loss will destroy the symmetry of the three-phase power supply, causing voltage and current imbalance, thereby affecting the operating stability of the load connected to the power supply (such as a servo motor). Therefore, phase loss detection is of great significance to ensure the stable operation of the power system and the safe use of equipment.

[0027] The traditional three-phase AC power phase loss detection circuit usually consists of a current limiting resistor, a high-voltage rectifier diode, a Zener diode, a DC optocoupler, and a pull-up resistor. The need to use multiple semiconductor devices, such as high-voltage rectifier diodes and Zener diodes, increases the circuit cost and complexity. In addition, this traditional detection circuit also has limitations in terms of application scenarios, especially in the case of mixed DC and AC connections.

[0028] Figure 1 FIG. 1 shows a circuit diagram of a phase loss detection device for a multi-phase AC power supply according to a first exemplary embodiment of the present utility model. Figure 1 In the illustrated embodiment, it is assumed that the AC power supply is a three-phase power supply, that is, it can provide three-phase L1, L2, L3 power supply signals. Correspondingly, the phase loss detection device includes three input pins, each of which is electrically connected to a corresponding one-phase power supply L1, L2, L3 in the three-phase AC power supply. In order to monitor the phase loss of the power supply, the device includes two optical couplers U1 and U2, which are especially AC optical couplers, and each optical coupler includes a primary side and a secondary side. Each primary side may, for example, include a photodiode PD1 or PD2 and another diode D1 or D2 connected in reverse parallel to the photodiode.

[0029] The primary side of the optical coupler U1 can be connected between the L1 phase and the L2 phase (i.e., between the first input pin and the second input pin of the phase loss detection device) to emit a corresponding optical signal based on the voltage difference between the L1 and L2 phases. The primary side of the optical coupler U2 can be connected between the L2 phase and the L3 phase (i.e., between the second input pin and the third input pin of the phase loss detection device) to emit another optical signal based on the voltage difference between the L2 and L3 phases. The secondary sides of the optical couplers U1 and U2 are electrically connected to each other in parallel, and each secondary side can output a corresponding electrical signal according to the optical signal emitted by the respective corresponding primary side.

[0030] In order to determine the phase loss condition of the power supply based on the electrical signal output by the secondary side of each optocoupler, the phase loss detection device may also include an output unit connected to the secondary sides of the optocouplers U1 and U2 to output the phase loss detection result based on the electrical signal provided by each secondary side.

[0031] Typically, the AC power supply used in industrial control equipment is a high-voltage power supply. In order to prevent the large current of the high-voltage power supply from damaging the electrical components (especially the optocoupler) in the phase loss detection device, a current limiting circuit can be set between the input pin of the phase loss detection device and the optocouplers U1 and U2. The current limiting circuit can limit the power signal provided at the input pin and provide it to the optocouplers U1 and U2 respectively.

[0032] Specifically, Figure 1 As shown in, the current limiting circuit may include three current limiting resistors R1, the first current limiting resistor is connected between the first input pin of the phase loss detection device (i.e., L1 phase) and the first input end of the optocoupler U1, the second current limiting resistor is connected between the second input pin of the device (i.e., L2 phase) and the second input end of the optocoupler U1, the first input end of the optocoupler U2 is connected to the second input end of the optocoupler U1, and the third current limiting resistor is connected between the third input pin of the device (i.e., L3 phase) and the second input end of the optocoupler U2.

[0033] To further perform voltage division and current limiting, the current limiting circuit may further include two voltage dividing resistors R2, wherein the first voltage dividing resistor is connected between the two input terminals of the optocoupler U1, and the second voltage dividing resistor is connected between the two input terminals of the optocoupler U2.

[0034] The resistance values ​​of the current limiting resistor R1 and the voltage dividing resistor R2 can be selected according to the power supply voltage of the three-phase AC power supply and the required current of the optical couplers U1 and U2 to ensure that the primary side of the optical coupler can be turned on and the secondary side transistor can be pulled down when the optical coupler is normal. As an example, the resistance value of the current limiting resistor R1 can be set to 68KΩ, and the resistance value of the voltage dividing resistor R2 can be set to 10KΩ.

[0035] exist Figure 1 In the embodiment of the invention, the secondary sides of the optical couplers U1 and U2 may include a phototransistor, and the output unit of the phase-loss detection device may include a DC source VCC and a pull-up resistor Ru directly electrically connected to the DC source VCC, wherein the collector of the phototransistor is connected to the pull-up resistor Ru, and the connection point between the two serves as the output pin Vout of the phase-loss detection device, and the emitter of the phototransistor is grounded. As an example, the resistance value of the pull-up resistor Ru can be set to 10KΩ.

[0036] Figure 2 A circuit diagram of a phase loss detection device for a multi-phase AC power supply according to a second exemplary embodiment of the present utility model is shown. Figure 1 and Figure 2 The two embodiments shown in the figure are basically consistent in the core circuit design of the phase loss detection device, including an optical coupler for signal transmission and processing, a current limiting resistor, and other power connections. The only difference between the two embodiments is the output unit. Specifically, in Figure 2 In the embodiment of the invention, the output unit includes a DC source VCC and a pull-down resistor Rd, wherein the collector of the phototransistor is connected to the DC source VCC, the emitter of the phototransistor is connected to the pull-down resistor Rd, and the connection point between the two serves as the output pin Vout of the phase loss detection device. As an example, the resistance value of the pull-down resistor Rd can be set to 10KΩ.

[0037] That is, the first embodiment uses a pull-up resistor Ru to ensure that the circuit maintains a high level state when there is no input signal, while the second embodiment uses a pull-down resistor Rd to maintain a low level state (when there is no input signal). The difference between the two output units allows the phase loss detection device of the utility model to adapt to different circuit design requirements and operating conditions, enhancing the flexibility and applicability of the device. In addition, the other circuit components and connection methods in the two embodiments remain unchanged, ensuring the consistency of basic functions and performance.

[0038] Although in Figure 1 and Figure 2In the embodiments, the circuit structure and working principle of the phase loss detection device of the utility model are described in detail by focusing on the three-phase AC power supply as an example, but it can be understood that the basic structure and working principle of the device are also applicable to multi-phase power supply systems. For N-phase power supply systems, the circuit can be expanded by adding a corresponding number of optocouplers to achieve monitoring of more phases. For example, for each additional phase, an optocoupler and a corresponding current limiting resistor can be added to ensure that each phase can be monitored independently. In addition, the pull-up / pull-down resistors and other auxiliary circuit components also need to be adjusted accordingly to adapt to the circuit characteristics of more phases. This modular design concept makes the phase loss detection device of the utility model not only suitable for three-phase power supply systems, but also can be flexibly expanded to multi-phase power supply systems, thereby improving the versatility and market adaptability of the device.

[0039] exist Figure 1 In the new design of the phase-loss detection device shown, its circuit structure is mainly composed of multiple current-limiting resistors, two AC optical couplers and a pull-up resistor. Among them, one input end of an optical coupler is connected to one input end of another optical coupler, and the other two input ends that are not connected to each other are connected to different phases of the AC power supply through the current-limiting resistor, and the pull-up resistor is connected in parallel with the two optical couplers. When the three-phase power supply is normal, the two optical couplers respectively generate staggered pulse signals, the secondary sides of the two optical couplers are connected in parallel to each other to realize the "AND" function, and the output Vout of the phase-loss detection device is a low level. When a phase is lost in the three-phase power supply, the outputs of the two optical couplers are either one high level and the other a pulse signal, or both are the same pulse signals, so the output Vout of the phase-loss detection device is a pulse signal. When the three-phase power supply is turned off as a whole, the outputs of the two optical couplers are both high levels, and the output Vout of the phase-loss detection device is also high. The detection result of the device is only related to the power supply state of the power supply, and can be applied to common AC and DC bus connections on the market. The device can perform detection operations after the power supply is turned on without the servo motor starting to work. The device quickly detects a phase loss in the mains, even with an input filter connected.

[0040] Figure 3 Shows Figure 1 Output simulation results of the phase loss detection device in . Figure 3 In the simulation results, the three-phase power supply works normally within 100ms; the three-phase power supply is phase-lost between 100ms and 200ms; and the power supply is turned off after 200ms. The phase-lost detection device can be integrated in a servo drive, for example, and the control chip of the servo drive can determine the phase-lost condition of the power supply by analyzing the output result of the phase-lost detection device. For example, when a phase-lost indication signal is received from the output unit of the phase-lost detection device, the control chip can interrupt the operation of the servo motor.

[0041] According to the phase loss detection device of the utility model, the traditional phase loss detection circuit design is improved. Specifically, the detection device of the utility model adopts a configuration structure of two AC photocouplers, avoiding the use of an external high-voltage rectifier bridge and a voltage-stabilizing diode, which not only simplifies the circuit structure, but also reduces the total cost and volume of the circuit. In addition, the phase loss detection device focuses on the monitoring of multi-phase AC power supply, and can perform effective detection during the power-on of electrical equipment and motor energy feedback. Even if there is an external input filter, it can quickly and accurately detect the input power supply status, thereby improving the accuracy and reliability of the phase loss detection result, and can adapt to a variety of power supply phase loss detection application scenarios (for example, AC and DC mixed connections).

[0042] In the present invention, the term "connection" refers to "electrical connection" or "communication connection". In addition, the terms "include" and "comprising" indicate that in addition to the units directly and clearly stated in the specification and claims, the technical solution of the present application does not exclude the situation of having other units that are not directly or clearly stated.

[0043] In the present invention, it can be understood by those skilled in the art that the disclosed system can be implemented in other ways. The system implementation methods described above are merely illustrative. For example, the division of the modules is merely a logical function division. There may be other division methods in actual implementation, such as the functions of multiple modules can be combined or the functions of a module can be further split. The modules in each implementation method of the present invention can be integrated into a processing unit, or each module can exist physically separately, or two or more modules can be integrated into one unit.

[0044] Although the utility model has been disclosed as a preferred embodiment, the utility model is not limited thereto. Various changes and modifications made without departing from the spirit and scope of the utility model should be included in the protection scope of the utility model, so the protection scope of the utility model should be based on the scope defined by the claims.

Claims

1. A phase loss detection device for a multi-phase AC power supply, characterized in that: The phase loss detection device comprises: A plurality of input pins, each input pin being electrically connected to a corresponding one-phase power supply (L1, L2, L3) in the multi-phase AC power supply; at least two optical couplers (U1, U2), each optical coupler comprising a primary side and a secondary side, the primary side of each optical coupler being disposed between two input pins of the plurality of input pins to transmit a corresponding optical signal based on a voltage difference between the two input pins, and the secondary sides of the respective optical couplers being electrically connected to each other in parallel and configured to output a corresponding electrical signal according to the optical signal transmitted by the respective corresponding primary side; and An output unit is connected to the secondary sides of the at least two optical couplers and is configured to output a detection result of the phase loss detection device based on the electrical signal provided by each secondary side.

2. The phase failure detection device according to claim 1, characterized in that: The at least two optical couplers are AC optical couplers, and the primary side of each AC optical coupler comprises a photodiode (PD1, PD2) and another diode (D1, D2) connected in reverse parallel to the photodiode.

3. The phase failure detection device according to claim 2, characterized in that: The multi-phase AC power supply is a three-phase power supply, and the phase loss detection device comprises three input pins and two optical couplers (U1, U2), wherein the first optical coupler (U1) is arranged between the first input pin and the second input pin, and the second optical coupler (U2) is arranged between the second input pin and the third input pin.

4. The phase failure detection device according to any one of claims 1 to 3, characterized in that: The phase loss detection device further includes a current limiting circuit, which is arranged between the multiple input pins and the at least two optical couplers and is configured to limit the current of the power supply signals output by the multiple input pins and provide them to the at least two optical couplers respectively.

5. The phase failure detection device according to claim 3, characterized in that: The phase loss detection device further includes three current limiting resistors (R1), wherein the first current limiting resistor is connected between the first input pin and the first input end of the first optocoupler (U1), the second current limiting resistor is connected between the second input pin and the second input end of the first optocoupler (U1), the first input end of the second optocoupler (U2) is connected to the second input end of the first optocoupler (U1), and the third current limiting resistor is connected between the third input pin and the second input end of the second optocoupler (U2).

6. The phase failure detection device according to claim 5, characterized in that: The phase loss detection device further includes two voltage-dividing resistors (R2), wherein the first voltage-dividing resistor is connected between the first input terminal and the second input terminal of the first optical coupler, and the second voltage-dividing resistor is connected between the first input terminal and the second input terminal of the second optical coupler.

7. The phase failure detection device according to claim 6, characterized in that: The resistance values ​​of the three current limiting resistors (R1) and the two voltage dividing resistors (R2) are set according to the power supply voltage of the three-phase power supply and the required current of the first optical coupler and the second optical coupler.

8. The phase failure detection device according to any one of claims 1 to 3, characterized in that: The secondary side of each optocoupler includes a phototransistor, and the output unit includes a DC source (VCC) and a pull-up resistor (Ru) directly electrically connected to the DC source (VCC), wherein the collector of the phototransistor is connected to the pull-up resistor (Ru), and the emitter of the phototransistor is grounded.

9. The phase failure detection device according to any one of claims 1 to 3, characterized in that: The secondary side of each optocoupler includes a phototransistor, and the output unit includes a DC source (VCC) and a pull-down resistor (Rd), wherein the collector of the phototransistor is connected to the DC source (VCC), and the emitter of the phototransistor is connected to the pull-down resistor (Rd).

10. A servo driver, characterized in that: The servo drive includes: The phase loss detection device according to any one of claims 1 to 9; and A control chip is connected to the output unit of the phase loss detection device and is configured to interrupt the operation of the servo motor when receiving a phase loss indication signal from the output unit.

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