Frequency detection device, method and electrical equipment

Abstract

The present invention discloses a frequency detection device, method and electrical equipment. The frequency detection device comprises: a voltage sampling module, a duty cycle adjustment module and a main control module; the input end of the voltage sampling module is connected to the three-phase electricity, the input end of the duty cycle adjustment module is connected to the output end of the voltage sampling module, and the output end of the duty cycle adjustment module is connected to the main control module; the voltage sampling module is used to sample the first voltage signal and the second voltage signal in the three-phase electricity; the duty cycle adjustment module is used to integrate the first voltage signal and the second voltage signal into a reference signal; the main control module is used to perform frequency detection according to the frequency and duty cycle of the reference signal. The present invention can effectively detect the frequency change of two-way signals, and the dual-wave detection more accurately reflects the frequency change of three-phase electricity, effectively improves the frequency detection accuracy, and improves the timeliness of three-phase electricity frequency protection, thereby improving the safety and stability of equipment use, saving the main control port, and improving chip utilization.

Description

Technical Field

[0001] The present invention relates to the technical field of frequency detection, and in particular to a frequency detection device, method and electrical equipment. Background Art

[0002] At present, with the continuous progress and use of power electronic devices, electricity consumption is becoming more and more intelligent and diversified. The quality of the power grid directly affects the safety and control logic of equipment.

[0003] For a three-phase power supply system, there is a phase difference between the three phases. The existing power grid frequency detection is usually a single-channel frequency monitoring, that is, detecting the frequency of any phase A, B, or C. When the three-phase frequencies of the power grid are inconsistent, the real power grid frequency cannot be detected, resulting in inaccurate frequency detection. In addition, if the detection circuit detects phase A, and a sudden frequency fault occurs just after the frequency of phase A is detected, then the next frequency detection will take exactly one detection cycle, resulting in untimely protection of the three-phase power grid. Summary of the invention

[0004] The embodiments of the present invention provide a frequency detection device, method and electrical equipment to at least solve the problem in the prior art that single-channel frequency detection leads to inaccurate frequency detection and untimely frequency protection.

[0005] In order to solve the above technical problems, an embodiment of the present invention provides a frequency detection device, comprising: a voltage sampling module, a duty cycle adjustment module and a main control module;

[0006] The input end of the voltage sampling module is connected to the three-phase power, the input end of the duty cycle adjustment module is connected to the output end of the voltage sampling module, and the output end of the duty cycle adjustment module is connected to the main control module;

[0007] The voltage sampling module is used to sample the first voltage signal and the second voltage signal in the three-phase electricity;

[0008] The duty cycle adjustment module is used to integrate the first voltage signal and the second voltage signal into a reference signal;

[0009] The main control module is used to perform frequency detection according to the frequency and duty cycle of the reference signal.

[0010] Optionally, the voltage sampling module includes: a first comparator and a second comparator;

[0011] The non-inverting input terminal of the first comparator is connected to the first phase line through a first resistor, the inverting input terminal of the first comparator is connected to the second phase line through a second resistor, the output terminal of the first comparator is connected to the first input terminal of the duty cycle adjustment module, and the output terminal of the first comparator outputs a square wave signal corresponding to the first voltage signal;

[0012] The non-inverting input terminal of the second comparator is connected to the second phase line through a third resistor, the inverting input terminal of the second comparator is connected to the third phase line through a fourth resistor, the output terminal of the second comparator is connected to the second input terminal of the duty cycle adjustment module, and the output terminal of the second comparator outputs a square wave signal corresponding to the second voltage signal.

[0013] Optionally, the duty cycle adjustment module includes: a first switch tube and a second switch tube;

[0014] The first end of the first switch tube serves as the first input end of the duty cycle adjustment module, the second end of the first switch tube is connected to the power supply through the fifth resistor, and the third end of the first switch tube is connected to the second end of the second switch tube;

[0015] The first end of the second switch tube serves as the second input end of the duty cycle adjustment module, the second end of the second switch tube is connected to the third end of the second switch tube through the sixth resistor, the third end of the second switch tube is grounded, and the second end of the second switch tube is also connected to the receiving port of the main control module through the seventh resistor.

[0016] Optionally, the first switch tube is a MOS tube or a triode, and the second switch tube is a MOS tube or a triode.

[0017] Optionally, the frequency detection device further includes: a clamping circuit connected to the output end of the duty cycle adjustment module and to the receiving port of the main control module.

[0018] Optionally, the clamping circuit includes: a first diode and a second diode connected in series, the anode of the first diode is connected to a power supply, the cathode of the first diode is connected to the anode of the second diode, the cathode of the second diode is grounded, and the connection point between the first diode and the second diode is connected to the output end of the duty cycle adjustment module and the receiving port of the main control module.

[0019] Optionally, the frequency detection device also includes: a protection module, connected to the main control module, used to perform a frequency fault protection action when the frequency of the reference signal is abnormal, and to perform a three-phase frequency imbalance protection action when the frequency of the reference signal is normal and the duty cycle of the reference signal is abnormal.

[0020] An embodiment of the present invention further provides an electrical device, comprising: the frequency detection device described in the embodiment of the present invention.

[0021] An embodiment of the present invention also provides a frequency detection method, which is applied to the frequency detection device described in the embodiment of the present invention, and the method includes: sampling a first voltage signal and a second voltage signal in three-phase electricity; integrating the first voltage signal and the second voltage signal into a reference signal; and performing frequency detection according to the frequency and duty cycle of the reference signal.

[0022] Optionally, frequency detection is performed based on the frequency and duty cycle of the reference signal, including: determining whether the frequency of the reference signal is within a preset frequency range; if the frequency of the reference signal is not within the preset frequency range, determining that the frequency of the first voltage signal is abnormal, and executing a frequency fault protection action.

[0023] Optionally, frequency detection is performed based on the frequency and duty cycle of the reference signal, including: determining whether the duty cycle of the reference signal is within a preset duty cycle range; if the duty cycle of the reference signal is not within the preset duty cycle range, and the frequency of the reference signal is within the preset frequency range, determining that the frequency of the second voltage signal is abnormal, and executing a three-phase frequency imbalance protection action.

[0024] Optionally, frequency detection is performed based on the frequency and duty cycle of the reference signal, including: if the frequency of the reference signal is within a preset frequency range and the duty cycle of the reference signal is within a preset duty cycle range, determining that the frequencies of the first voltage signal and the second voltage signal are normal.

[0025] By applying the technical solution of the present invention, two voltage signals in three-phase electricity are collected through a voltage sampling module, and the two voltage signals are integrated into a reference signal through a duty cycle adjustment module. The frequency change of the two signals can be effectively detected according to the frequency and duty cycle of the reference signal. The dual-wave detection more accurately reflects the frequency change of the three-phase electricity, effectively improves the frequency detection accuracy and reliability, and improves the timeliness of the three-phase electricity frequency protection, thereby improving the safety and stability of equipment use, and solving the problem of inaccurate frequency detection and untimely frequency protection caused by single-channel frequency detection. In addition, the duty cycle adjustment module transmits a reference signal to the main control module, which only needs to occupy one port of the main control module, saving the main control port and improving chip utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a schematic diagram of a frequency detection device provided by an embodiment of the present invention Figure 1 ;

[0027] Figure 2 is a schematic diagram of a frequency detection device provided by an embodiment of the present invention Figure 2 ;

[0028] Figure 3 is a schematic diagram of a frequency detection device provided by an embodiment of the present invention Figure 3 ;

[0029] Figure 4 is a schematic diagram of waveforms of output signals of comparators L1 and L2 provided in an embodiment of the present invention;

[0030] Figure 5 is a flow chart of a frequency detection method provided by an embodiment of the present invention;

[0031] Figure 6 It is a flow chart of dual-wave check frequency detection provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] It should be noted that the terms "first", "second", etc. in the specification, claims and drawings of the present invention are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0034] The embodiment of the present invention provides a frequency detection device, which can be used to detect the frequency of three-phase electricity, for example, it can be suitable for detecting the frequency of a three-phase power grid or a three-phase power supply, etc., and can achieve high-precision frequency detection and timely protection for three-phase electricity of any frequency. Figure 1 As shown, the frequency detection device includes: a voltage sampling module 10, a duty cycle adjustment module 20 and a main control module 30.

[0035] The input end of the voltage sampling module 10 is connected to the three-phase power, the input end of the duty cycle adjustment module 20 is connected to the output end of the voltage sampling module 10 , and the output end of the duty cycle adjustment module 20 is connected to the main control module 30 .

[0036] The voltage sampling module 10 is used to sample the first voltage signal and the second voltage signal in the three-phase electricity. The first voltage signal and the second voltage signal are the voltages between two adjacent phases in the three-phase electricity. For example, for the three-phase abc, the first voltage signal is the voltage Ubc between the b-phase and the c-phase, and the second voltage signal is the voltage Uca between the c-phase and the a-phase, or the first voltage signal is the voltage Uab between the a-phase and the b-phase, and the second voltage signal is the voltage Ubc between the b-phase and the c-phase.

[0037] The duty cycle adjustment module 20 is used to integrate the first voltage signal and the second voltage signal into a reference signal. The reference signal can reflect the frequency of the three-phase electricity. Specifically, the voltage signal in the three-phase electricity is an AC sinusoidal signal, and the voltage sampling module 10 samples the AC sinusoidal signal to obtain a square wave signal. The reference signal output by the duty cycle adjustment module 20 is a rectangular wave signal.

[0038] The main control module 30 is used to perform frequency detection according to the frequency and duty cycle of the reference signal. The main control module 30 may be a DSP chip.

[0039] In this embodiment, the voltage sampling module 10 collects two voltage signals in the three-phase electricity, and the duty cycle adjustment module 20 integrates the two voltage signals into a reference signal. According to the frequency and duty cycle of the reference signal, the frequency change of the two signals can be effectively detected. The dual-wave detection more accurately reflects the frequency change of the three-phase electricity, effectively improves the frequency detection accuracy and reliability, and improves the timeliness of the three-phase electricity frequency protection, thereby improving the safety and stability of the equipment, and solving the problem of inaccurate frequency detection and untimely frequency protection caused by single-channel frequency detection. In addition, the duty cycle adjustment module 20 transmits a reference signal to the main control module 30, which only needs to occupy one port of the main control module 30, saving the main control port and improving the chip utilization.

[0040] The voltage sampling module 10 includes a first comparator L1 and a second comparator L2.

[0041] The non-inverting input terminal of the first comparator L1 is connected to the first phase line through the first resistor R1, the inverting input terminal of the first comparator L1 is connected to the second phase line through the second resistor R2, the output terminal of the first comparator L1 is connected to the first input terminal of the duty cycle adjustment module 20, and the output terminal of the first comparator L1 outputs a square wave signal corresponding to the first voltage signal.

[0042] The non-inverting input terminal of the second comparator L2 is connected to the second phase line through the third resistor R3, the inverting input terminal of the second comparator L2 is connected to the third phase line through the fourth resistor R4, the output terminal of the second comparator L2 is connected to the second input terminal of the duty cycle adjustment module 20, and the output terminal of the second comparator L2 outputs a square wave signal corresponding to the second voltage signal.

[0043] The first phase line, the second phase line and the third phase line are three phase lines in the three-phase electricity. For example, the first phase line is the a phase line, the second phase line is the b phase line, and the third phase line is the c phase line, then the first voltage signal is Uab, and the second voltage signal is Ubc. Figure 2 As shown, the first comparator L1 outputs a square wave signal corresponding to Uab, and the second comparator L2 outputs a square wave signal corresponding to Ubc.

[0044] The resistance values ​​of the first resistor R1, the second resistor R2, the third resistor R3, and the fourth resistor R4 can be set according to actual needs, and the resistance values ​​of the first resistor R1 and the second resistor R2 are not equal, and the resistance values ​​of the third resistor R3 and the fourth resistor R4 are not equal. In practical applications, the first comparator L1 and the second comparator L2 can be comparators with exactly the same configuration, that is, the supply voltages of the two comparators are the same, the resistance values ​​of the first resistor R1 and the third resistor R3 are equal, and the resistance values ​​of the second resistor R2 and the fourth resistor R4 are equal.

[0045] If the value of the comparator's non-inverting input is greater than the value of the inverting input, the comparator outputs a high level; if the value of the comparator's non-inverting input is less than the value of the inverting input, the comparator outputs a low level.

[0046] In this embodiment, the zero-crossing detection is implemented by the first comparator L1 and the second comparator L2, and the AC sinusoidal signal of a certain frequency is converted into a corresponding square wave signal to implement voltage signal sampling.

[0047] refer to Figure 2 The duty cycle adjustment module 20 includes: a first switch tube G1 and a second switch tube G2.

[0048] The first end of the first switch tube G1 serves as the first input end of the duty cycle adjustment module 20 , the second end of the first switch tube G1 is connected to the power supply Vcc through the fifth resistor R5 , and the third end of the first switch tube G1 is connected to the second end of the second switch tube G2 .

[0049] The first end of the second switch tube G2 serves as the second input end of the duty cycle adjustment module 20, the second end of the second switch tube G2 is connected to the third end of the second switch tube G2 through the sixth resistor R6, the third end of the second switch tube G2 is grounded, and the second end of the second switch tube G2 is also connected to the receiving port of the main control module 30 through the seventh resistor R7. The end connected to the main control module 30 is the output end of the duty cycle adjustment module 20. The resistance value of the sixth resistor R6 is much greater than the resistance value of the fifth resistor R5.

[0050] In this embodiment, two voltage signals are processed by the first switch tube G1 and the second switch tube G2 to obtain a rectangular wave signal (i.e., the reference signal Uout0) which is transmitted to the main control module 30. By monitoring the duty cycle and frequency of the reference signal, the frequency detection accuracy can be improved, frequency fault protection and three-phase frequency imbalance processing can be quickly performed, and the main control interface can be saved, thereby improving chip utilization.

[0051] The first switch tube G1 may be a MOS tube or a triode, and the second switch tube G2 may be a MOS tube or a triode. Specifically, the first end of the switch tube may be the base of the triode or the gate of the MOS tube; the second end of the switch tube may be the collector of the triode or the drain of the MOS tube; the third end of the switch tube may be the emitter of the triode or the source of the MOS tube.

[0052] In one embodiment, the frequency detection device may further include: a clamping circuit connected to the output end of the duty cycle adjustment module 20 and to the receiving port of the main control module 30. The main control module 30 has an input voltage range requirement, and the clamping circuit is used to limit the input voltage of the receiving port of the main control module 30 to ensure that the voltage input to the main control module 30 does not exceed the range and is stable, thereby protecting the main control module 30.

[0053] like Figure 2 As shown, the clamping circuit includes: a first diode D1 and a second diode D2 connected in series, the anode of the first diode D1 is connected to the power supply, the cathode of the first diode D1 is connected to the anode of the second diode D2, the cathode of the second diode D2 is grounded, and the connection point between the first diode D1 and the second diode D2 is connected to the output end of the duty cycle adjustment module 20 and the receiving port of the main control module 30. Of course, Figure 2 The clamping circuit in FIG. 1 is only an example, and other devices may also be used to form a clamping circuit.

[0054] like Figure 3 As shown, the frequency detection device may further include: a protection module 40, connected to the main control module 30, for performing a frequency fault protection action when the frequency of the reference signal is abnormal, and performing a three-phase frequency imbalance protection action when the frequency of the reference signal is normal and the duty cycle of the reference signal is abnormal. Figure 3 In the embodiment, the voltage sampling module 10 includes: a first voltage signal sampling unit 11 and a second voltage signal sampling unit 12. The first voltage signal sampling unit 11 is used to sample the first voltage signal, which is equivalent to the above-mentioned first comparator L1; the second voltage signal sampling unit 12 is used to sample the second voltage signal, which is equivalent to the above-mentioned second comparator L2.

[0055] Among them, the reference signal corresponds to a standard frequency and duty cycle, which can be set according to the actual situation of the three-phase electricity detected, for example, the standard frequency is 50Hz, and the standard duty cycle is 33.33%. In order to determine whether the frequency and duty cycle of the reference signal are normal, a certain fluctuation is allowed on the basis of the standard frequency and the standard duty cycle to obtain a preset frequency range and a preset duty cycle range, for example, the preset frequency range is 50Hz±2Hz, and the preset duty cycle range is 33.33%±1.3%. If the frequency of the reference signal is not within the preset frequency range, it means that the frequency of the reference signal is abnormal; if the duty cycle of the reference signal is not within the preset duty cycle range, it means that the duty cycle of the reference signal is abnormal.

[0056] like Figure 4 As shown, L1_out represents the L1 output signal, and L2_out represents the L2 output signal.

[0057] At t1, G1 is turned on, G2 is turned off, R5 and R6 divide the voltage, R7 plays a current limiting role, Uout0 = Vcc × R6 / (R6+R5), R6 resistance is much greater than R5, Uout0 is a high level. For example, R5 = 1kΩ, R6 = 100kΩ, Uout0 = 3.3 × 100 / 101, approximately equal to 3.3V, for the main control module 30, greater than 1.2V is a high level.

[0058] At t2, both G1 and G2 are turned on, Uout0 is directly connected to the 0V potential point, the output of Uout0 is the voltage drop of G2 tube, Uout0 is approximately equal to 0V, and Uout0 is a low level.

[0059] At t3, G1 is disconnected and G2 is turned on. At this time, Uout0 is pulled down to ground through R6, and Uout0 is at a low level.

[0060] At t4, both G1 and G2 are turned off. At this time, Uout0 is pulled down to ground through R6, and Uout0 is at a low level.

[0061] It can be seen that the L1 output signal and the L2 output signal together constitute the reference signal Uout0. No matter how the waveform of the L2 output signal changes, as long as the frequency of the L1 output signal is determined, Uout0 is a high level at t1 and a low level at t2, t3 and t4. In other words, no matter how the waveform of the L2 output signal changes, Uout0 must exist in the above four time periods from t1 to t4. The above four time periods from t1 to t4 constitute a cycle, which is exactly the same as the cycle of the L1 output signal. Therefore, the frequency of Uout0 is the same as the frequency of the L1 output signal, and the waveform change of the L2 output signal only affects the duty cycle of Uout0.

[0062] Exemplarily, for a three-phase power grid, Uab and Ubc are sinusoidal signals of a certain frequency, and the corresponding square wave signals are obtained through the first comparator L1 and the second comparator L2. If the power grid is normal, the L1 output signal and the L2 output signal are square wave signals with a phase difference of 120°, and the frequencies are both the power grid frequency, and then the standard frequency of the reference signal Uout0 is the power grid frequency, and the standard duty cycle is 33.33%, which allows a certain fluctuation. Uab affects the frequency of the detected reference signal, and Ubc affects the duty cycle of the detected reference signal.

[0063] If the frequency and duty cycle of the reference signal are normal, it means that the frequencies of the first voltage signal and the second voltage signal are normal. If the frequency of the reference signal is abnormal, it means that the frequency of the first voltage signal is abnormal, and the frequency fault protection action can be executed at this time. If the frequency of the reference signal is normal and the duty cycle is abnormal, it means that the frequency of the second voltage signal is abnormal and the frequency of the three-phase electricity is unbalanced, and the three-phase frequency imbalance protection action can be executed at this time.

[0064] The frequency fault protection action may include: disconnecting the main circuit breaker connected to the three-phase electricity, the system shuts down, and the fault code displays the frequency fault. The three-phase frequency imbalance protection action may include: disconnecting the main circuit breaker connected to the three-phase electricity, the system shuts down, and reports the three-phase frequency imbalance fault code.

[0065] This embodiment can timely and effectively determine frequency anomalies based on the frequency and duty cycle of the reference signal, prevent frequency detection from being inadequate, and perform corresponding protection actions in a timely manner.

[0066] The embodiment of the present invention further provides an electrical device, comprising: the frequency detection device described in the above embodiment. The above frequency detection device can be applied to various power electronic frequency sampling occasions and electrical devices, such as inverters or centrifuges, electrical equipment, automobiles, etc.

[0067] The embodiment of the present invention further provides a frequency detection method, which is applied to the frequency detection device described in the above embodiment. The explanation of terms that are the same or corresponding to the above embodiment will not be repeated in this embodiment.

[0068] Figure 5 is a flow chart of a frequency detection method provided by an embodiment of the present invention, such as Figure 5 As shown, the method comprises the following steps:

[0069] S501, sampling a first voltage signal and a second voltage signal in three-phase electricity.

[0070] S502: Integrate the first voltage signal and the second voltage signal into a reference signal.

[0071] S503, performing frequency detection according to the frequency and duty cycle of the reference signal.

[0072] The first voltage signal and the second voltage signal are voltages between two adjacent phases in the three-phase electricity, and the reference signal can reflect the frequency of the three-phase electricity.

[0073] This embodiment collects two voltage signals in the three-phase electricity and integrates the two voltage signals into a reference signal. The frequency change of the two signals can be effectively detected according to the frequency and duty cycle of the reference signal. The dual-wave detection more accurately reflects the frequency change of the three-phase electricity, effectively improves the frequency detection accuracy and reliability, and improves the timeliness of the three-phase electricity frequency protection, thereby improving the safety and stability of equipment use, and solving the problem of inaccurate frequency detection and untimely frequency protection caused by single-channel frequency detection.

[0074] Frequency detection is performed based on the frequency and duty cycle of the reference signal, including: determining whether the frequency of the reference signal is within a preset frequency range; if the frequency of the reference signal is not within the preset frequency range, determining that the frequency of the first voltage signal is abnormal, and executing a frequency fault protection action. In this way, frequency abnormalities can be detected quickly and accurately, and protection can be performed in a timely manner.

[0075] Frequency detection is performed based on the frequency and duty cycle of the reference signal, including: determining whether the duty cycle of the reference signal is within a preset duty cycle range; if the duty cycle of the reference signal is not within the preset duty cycle range, and the frequency of the reference signal is within the preset frequency range, determining that the frequency of the second voltage signal is abnormal, and performing a three-phase frequency imbalance protection action. In this way, frequency imbalance can be detected quickly and accurately, and protection can be performed in a timely manner.

[0076] Frequency detection is performed based on the frequency and duty cycle of the reference signal, including: if the frequency of the reference signal is within a preset frequency range and the duty cycle of the reference signal is within a preset duty cycle range, it is determined that the frequencies of the first voltage signal and the second voltage signal are normal and the system or device is operating normally.

[0077] The order of judging whether the frequency of the reference signal is normal and whether the duty cycle of the reference signal is normal can be set according to the actual situation. The two can be judged at the same time, or the frequency can be judged first and then the duty cycle, or the duty cycle can be judged first and then the frequency.

[0078] like Figure 6 As shown, it is a flow chart of double-wave calibration frequency detection, which includes the following steps:

[0079] S601, start.

[0080] S602, system power failure detection.

[0081] S603, check whether the frequency of the reference signal is normal, if not, proceed to S604, if yes, proceed to S605.

[0082] S604, performing frequency fault protection.

[0083] S605, check whether the duty cycle of the reference signal is normal, if not, proceed to S606, if yes, proceed to S607.

[0084] S606, the system performs three-phase frequency imbalance protection.

[0085] S607, the system operates normally.

[0086] S608, end.

[0087] The dual-wave calibration frequency detection scheme of this embodiment can effectively detect the frequency changes of two signals through one signal collection, greatly improving the functional utilization of the main control chip, realizing high-precision frequency detection, improving the frequency detection accuracy and protection timeliness, and improving the reliability of frequency detection and the safety and stability of the control equipment. It has calibration and protection functions for a variety of different frequency waveforms. The reference signal Uout0 waveform can be visually detected by an oscilloscope. By inputting two voltage samples and monitoring the Uout0 waveform, the duty cycle and frequency changes can be visually viewed.

[0088] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A frequency detection device, characterized in that: include: Voltage sampling module, duty cycle adjustment module and main control module; The input end of the voltage sampling module is connected to the three-phase power, the input end of the duty cycle adjustment module is connected to the output end of the voltage sampling module, and the output end of the duty cycle adjustment module is connected to the main control module; The voltage sampling module is used to sample a first voltage signal and a second voltage signal in the three-phase electricity, wherein the first voltage signal and the second voltage signal are both line voltages; The duty cycle adjustment module is used to integrate the first voltage signal and the second voltage signal into a reference signal; The main control module is used to perform frequency detection according to the frequency and duty cycle of the reference signal; The duty cycle adjustment module includes: a first switch tube and a second switch tube; The first end of the first switch tube serves as the first input end of the duty cycle adjustment module, the second end of the first switch tube is connected to the power supply through the fifth resistor, and the third end of the first switch tube is connected to the second end of the second switch tube; The first end of the second switch tube serves as the second input end of the duty cycle adjustment module, the second end of the second switch tube is connected to the third end of the second switch tube through a sixth resistor, the third end of the second switch tube is grounded, and the second end of the second switch tube is further connected to the receiving port of the main control module through a seventh resistor; The first voltage signal is connected to the first end of the first switch tube, and the second voltage signal is connected to the first end of the second switch tube; The first switch tube is a MOS tube or a triode, the second switch tube is a MOS tube or a triode, the first end of the switch tube is the base of the triode or the gate of the MOS tube, the second end of the switch tube is the collector of the triode or the drain of the MOS tube, and the third end of the switch tube is the emitter of the triode or the source of the MOS tube.

2. The frequency detection device according to claim 1, characterized in that: The voltage sampling module includes: a first comparator and a second comparator; The non-inverting input terminal of the first comparator is connected to the first phase line through a first resistor, the inverting input terminal of the first comparator is connected to the second phase line through a second resistor, the output terminal of the first comparator is connected to the first input terminal of the duty cycle adjustment module, and the output terminal of the first comparator outputs a square wave signal corresponding to the first voltage signal; The non-inverting input terminal of the second comparator is connected to the second phase line through a third resistor, the inverting input terminal of the second comparator is connected to the third phase line through a fourth resistor, the output terminal of the second comparator is connected to the second input terminal of the duty cycle adjustment module, and the output terminal of the second comparator outputs a square wave signal corresponding to the second voltage signal.

3. The frequency detection device according to claim 1, characterized in that: Also includes: The clamping circuit is connected to the output end of the duty cycle adjustment module and to the receiving port of the main control module.

4. The frequency detection device according to claim 3, characterized in that: The clamping circuit includes: a first diode and a second diode connected in series, the anode of the first diode is connected to a power supply, the cathode of the first diode is connected to the anode of the second diode, the cathode of the second diode is grounded, and the connection point between the first diode and the second diode is connected to the output end of the duty cycle adjustment module and the receiving port of the main control module.

5. The frequency detection device according to any one of claims 1 to 4, characterized in that: Also includes: A protection module is connected to the main control module and is used to perform a frequency fault protection action when the frequency of the reference signal is abnormal, and to perform a three-phase frequency imbalance protection action when the frequency of the reference signal is normal and the duty cycle of the reference signal is abnormal.

6. An electrical device, characterized in that: include: The frequency detection device according to any one of claims 1 to 5.

7. A frequency detection method, characterized in that: The frequency detection device applied to any one of claims 1 to 5, the method comprising: Sampling a first voltage signal and a second voltage signal in three-phase electricity; Integrate the first voltage signal and the second voltage signal into a reference signal; Frequency detection is performed according to the frequency and duty cycle of the reference signal.

8. The method according to claim 7, characterized in that Performing frequency detection according to the frequency and duty cycle of the reference signal includes: Determining whether the frequency of the reference signal is within a preset frequency range; If the frequency of the reference signal is not within the preset frequency range, it is determined that the frequency of the first voltage signal is abnormal, and a frequency fault protection action is performed.

9. The method according to claim 7, characterized in that: Performing frequency detection according to the frequency and duty cycle of the reference signal includes: Determining whether the duty cycle of the reference signal is within a preset duty cycle range; If the duty cycle of the reference signal is not within the preset duty cycle range, and the frequency of the reference signal is within the preset frequency range, it is determined that the frequency of the second voltage signal is abnormal, and a three-phase frequency imbalance protection action is performed.

10. The method according to any one of claims 7 to 9, characterized in that Performing frequency detection according to the frequency and duty cycle of the reference signal includes: If the frequency of the reference signal is within a preset frequency range and the duty cycle of the reference signal is within a preset duty cycle range, it is determined that the frequencies of the first voltage signal and the second voltage signal are both normal.

Images