Power equipment and overcurrent protection method for power equipment

Abstract

The embodiment of the invention relates to power equipment and an overcurrent protection method for the power equipment. The apparatus includes: a rectifier bridge configured to rectify an input voltage to output a rectified voltage; a first voltage sensor configured to generate a first voltage signal indicating a magnitude of one of the input voltage or the rectified voltage; a current sensor configured to generate a current signal indicating the magnitude of the output current of the rectifier bridge; a threshold current setting unit configured to dynamically determine a threshold current based on the first voltage signal; and a control unit configured to generate a control signal to disable the driver of the rectifier bridge in response to the current signal exceeding a threshold current. Through the technical scheme of the embodiment of the invention, a response can be quickly made to forbid the driver of the rectifier bridge under the condition of overcurrent / overvoltage of the over-power equipment, so that an inverter and a load are prevented from being damaged, and the safety of the equipment is enhanced.

Description

Technical Field

[0001] The present disclosure relates to the field of power equipment, and more specifically, to power equipment and an overcurrent protection method for the power equipment. Background Art

[0002] The inverter is used to convert direct current into industrial frequency alternating current required by the load. It is widely used in solar photovoltaic power generation, wind power generation, battery energy storage, automotive electronics and other fields. It is usually necessary to set overcurrent protection for the inverter. The traditional solution usually sets a fixed overcurrent protection threshold. When the output current exceeds the protection threshold, the power supply to the inverter is cut off to stop the inverter from working, or the output current of the inverter is reduced to protect the inverter and the load from damage. The fixed overcurrent protection threshold will cause the protection circuit to respond slowly in some cases, such as when a short circuit or overload occurs at a higher output voltage, so there is still a risk of damage to the inverter or the load. Summary of the invention

[0003] Embodiments of the present disclosure provide an electric power device and an overcurrent protection method for the electric power device to at least solve one of the above and other potential problems of the prior art.

[0004] According to one aspect of the present disclosure, a power device is provided. The device includes: a rectifier bridge configured to rectify an input voltage to output a rectified voltage; a first voltage sensor configured to generate a first voltage signal indicating the magnitude of one of the input voltage or the rectified voltage; a current sensor configured to generate a current signal indicating the magnitude of an output current of the rectifier bridge; a threshold current setting unit configured to dynamically determine a threshold current based on the first voltage signal; and a control unit configured to generate a control signal in response to the current signal exceeding the threshold current to disable a driver of the rectifier bridge.

[0005] In the above embodiment, by determining a dynamic current threshold based on the first voltage signal, the control unit can respond quickly when the output current exceeds the threshold, so that the driver of the rectifier bridge stops outputting, thereby protecting the inverter and the load from damage caused by overcurrent and enhancing the safety of the equipment.

[0006] In some embodiments, the power device further comprises a second voltage sensor configured to generate a second voltage signal indicating the magnitude of the other voltage of the input voltage or the rectified voltage; wherein the threshold current setting unit dynamically determines the threshold current based on the first voltage signal and / or the second voltage signal.

[0007] In the above embodiment, by generating the second voltage signal, the threshold current setting unit can dynamically determine the threshold current based on the first voltage signal and / or the second voltage signal, thereby determining a more accurate threshold current as needed to further improve the safety of the device.

[0008] In some embodiments, the threshold current setting unit further includes an analog-to-digital converter and a processor. The analog-to-digital converter is configured to sample and analog-to-digital convert the first voltage signal and / or the second voltage signal, respectively, to generate a first digital voltage signal and / or a second digital voltage signal, respectively. The processor is configured to generate a threshold current based on the first digital voltage signal and / or the second digital voltage signal.

[0009] In the above embodiment, by sampling the first voltage signal and the second voltage signal and converting them into digital signals, the interference signal therein can be filtered out; and by processing them to generate a threshold current, it can be used as a reference for judging whether the output current is in an overcurrent state. In this way, a dynamic threshold current can be generated to quickly respond when an overcurrent occurs.

[0010] In some embodiments, the power device further comprises a sampling unit configured to sample and convert the current signal into current / voltage, and output a first conversion voltage signal corresponding to a positive half cycle of the current signal and a second conversion voltage signal corresponding to a negative half cycle of the current signal.

[0011] In the above embodiment, the interference signal can be filtered out by sampling the current signal, and the converted signal can be input into the comparator through current / voltage conversion to realize real-time monitoring of the output current.

[0012] In some embodiments, the control unit includes: a first digital-to-analog converter configured to convert a threshold current in a positive half cycle into a first analog threshold signal; and a second digital-to-analog converter configured to convert a threshold current in a negative half cycle into a second analog threshold signal.

[0013] In the above embodiment, by converting the threshold current in digital form into an analog signal, the analog signal can be conveniently input into the comparator for comparison with the first conversion voltage signal and the second conversion voltage signal.

[0014] In some embodiments, the control unit also includes: a first comparator, configured to generate a first control signal in response to the first conversion voltage signal exceeding the first analog threshold signal; and a second comparator, configured to output a second control signal in response to the second conversion voltage signal exceeding the second analog threshold signal; wherein either the first control signal or the second control signal is used as the control signal.

[0015] In the above embodiment, by setting the first and second comparators, it is possible to determine whether there is overcurrent during the positive and negative half cycles, respectively. In this way, real-time monitoring of the output current can be achieved.

[0016] In some embodiments, the control unit further includes: a first filter configured to filter the first control signal to generate a first filtered signal; and a second filter configured to filter the second control signal to generate a second filtered signal.

[0017] In the above embodiment, the interference signal can be filtered out by setting a filter, thereby ensuring that the output control signal is effective.

[0018] In some embodiments, the power device further includes: a constant overcurrent protection unit configured to output a third control signal in response to an output current exceeding a constant threshold current; and / or a constant overvoltage protection unit configured to output a fourth control signal in response to an input voltage exceeding a constant threshold voltage. The third control signal and the fourth control signal are selectively used to disable the driver of the rectifier bridge, respectively.

[0019] In the above embodiment, not only is overcurrent protection implemented by setting a dynamic threshold current, but constant overcurrent protection and constant overvoltage protection are also combined, so that when any one of the protection conditions is triggered, the protection function is activated, thereby further ensuring the safety and reliability of the equipment.

[0020] In the above embodiment, the constant overcurrent protection unit includes: a third comparator, configured to output a fifth control signal in response to the first conversion voltage signal exceeding the first constant threshold voltage signal converted from the first constant threshold current signal in the constant threshold current; a fourth comparator, configured to output a sixth control signal in response to the second conversion voltage signal exceeding the second constant threshold voltage signal converted from the second constant threshold current signal in the constant threshold current; and a first OR gate, configured to perform a logical OR operation on the fifth control signal and the sixth control signal to generate a third control signal.

[0021] In the above embodiment, by comparing the corresponding conversion voltage signal with the corresponding first and second constant threshold current signals, it is possible to determine whether the output current exceeds the predetermined threshold current. If so, a corresponding control signal is output to disable the inverter of the rectifier bridge.

[0022] In some embodiments, the power device also includes: a logic circuit configured to perform a logical OR operation on a control signal generated by a control unit, a third control signal generated by a constant overcurrent protection unit, and a fourth control signal generated by a constant overvoltage protection unit to output a high-level signal as a control signal; and a driver configured to stop outputting a drive signal for driving a rectifier bridge in response to receiving a control signal.

[0023] In the above embodiment, by performing logical operations on the signals output by the dynamic current protection, the constant current protection and the constant voltage protection, when any protection condition is met, the protection is triggered to stop the operation of the driver, thereby further improving the safety of the device.

[0024] In some embodiments, the logic circuit includes: a second OR gate, configured to perform a logical OR operation on a first input signal and a second input signal, wherein the first input signal is a signal selected from one of a first filtered signal and an unfiltered first control signal; and the second input signal is a signal selected from one of a second filtered signal and an unfiltered second control signal.

[0025] In the above embodiment, by performing a logic OR operation on the first input signal and the second input signal, when a current exceeding the threshold value appears in either the positive half cycle or the negative half cycle, the overcurrent protection is activated.

[0026] In some embodiments, the rectifier bridge includes: a first bridge arm, including a first controllable switch and a second controllable switch connected in series to a first node; and a second bridge arm, including a third controllable switch and a fourth controllable switch connected in series to a second node, wherein two ends of the second bridge arm are connected in parallel with two ends of the first bridge arm to a third node and a fourth node, respectively.

[0027] In the above embodiment, a rectifier bridge is formed by the first to fourth controllable switches to perform intermediate rectification on the input voltage to realize the inversion function.

[0028] In some embodiments, the power device also includes: an inductor, a first end of the inductor is coupled to a first node; a first capacitor, a first end of the first capacitor is coupled to a second end of the inductor, and a second end of the first capacitor is coupled to a fourth node, wherein both ends of the first capacitor are suitable for connecting a load in parallel; and a second capacitor, both ends of the second capacitor are coupled between a third node and a fourth node, respectively, wherein an input voltage is applied between the third node and the fourth node.

[0029] In the above embodiment, the LC filter circuit formed by the inductor and the first capacitor can filter out the AC interference signal to obtain a rectified output with a desired waveform.

[0030] In some embodiments, the current sensor is configured to sense the current flowing through the inductor to generate a current signal; the first voltage sensor is configured to sense the voltage across the second capacitor to generate a first voltage signal; and the second voltage sensor is configured to sense the root mean square value of the voltage across the first capacitor to generate a second voltage signal.

[0031] In the above embodiment, by sensing the voltage across the first capacitor and the second capacitor, the threshold current can be determined subsequently; by sensing the current flowing through the inductor, it can be compared with the threshold current to determine whether overcurrent occurs.

[0032] According to another aspect of an embodiment of the present disclosure, an overcurrent protection method for an electrical device is provided, wherein the electrical device includes a rectifier bridge, which is configured to rectify an input voltage to output a rectified voltage. The method includes: generating a first voltage signal indicating a magnitude of a voltage based on an input voltage or a rectified voltage; generating a current signal indicating a magnitude of an output current based on an output current of the rectifier bridge; dynamically setting a threshold current based on the first voltage signal; and generating a control signal in response to the current signal exceeding the threshold current to disable a driver of the rectifier bridge.

[0033] In the above embodiment, by determining a dynamic current threshold based on the first voltage signal, a control signal can be quickly output when the output current exceeds the threshold, so that the driver of the rectifier bridge stops outputting, thereby protecting the inverter and the load from damage caused by overcurrent and enhancing the safety of the equipment.

[0034] In some embodiments, the method further includes generating a second voltage signal indicating a magnitude of the other voltage based on the other voltage of the input voltage or the rectified voltage; wherein the threshold current is dynamically determined based on the first voltage signal and / or the second voltage signal.

[0035] In the above embodiment, by generating the second voltage signal, the threshold current can be dynamically determined based on the first voltage signal and / or the second voltage signal, thereby determining a more accurate threshold current as needed to further improve the safety of the device.

[0036] In some embodiments, dynamically setting the threshold current based on the first voltage signal and / or the second voltage signal includes: sampling and analog-to-digital converting the first voltage signal and / or the second voltage signal, respectively, to generate a first digital voltage signal and / or a second digital voltage signal, respectively; and generating the threshold current based on the first digital voltage signal and / or the second digital voltage signal.

[0037] In the above embodiment, by sampling the first voltage signal and the second voltage signal and converting them into digital signals, the interference signal therein can be filtered out; by processing them to generate a threshold current, it can be used as a reference for determining whether the output current is in an overcurrent state.

[0038] In some embodiments, the method further includes: sampling and current / voltage conversion of the current signal, and outputting a first conversion voltage signal corresponding to a positive half cycle of the current signal and a second conversion voltage signal corresponding to a negative half cycle of the current signal respectively.

[0039] In the above embodiment, the interference signal can be filtered out by sampling the current signal; and the current / voltage conversion is convenient for inputting the comparator to realize real-time monitoring of the output current.

[0040] In some embodiments, the method also includes: converting the threshold current in the positive half cycle into a first analog threshold signal; converting the threshold current in the negative half cycle into a second analog threshold signal; generating a first control signal in response to the first conversion voltage signal exceeding the first analog threshold signal; or, outputting a second control signal in response to the second conversion voltage signal exceeding the second analog threshold signal; and using either the first control signal or the second control signal as a control signal to disable the driver of the rectifier bridge.

[0041] In the above embodiment, by converting the threshold current in digital form into an analog signal, it can be conveniently input into the comparator for comparison with the first conversion voltage signal and the second conversion voltage signal. By setting the first and second comparators, it can be determined whether there is an overcurrent during the positive and negative half cycles, respectively. In this way, the output current can be monitored in real time.

[0042] In some embodiments, a control signal is output to disable a driver of the rectifier bridge in any of the following situations: the current signal exceeds a threshold current; the output current exceeds a constant threshold current; and the input voltage exceeds a constant threshold voltage.

[0043] In the above embodiments, by setting different over-current / over-voltage protection conditions, protection can be implemented when any condition is met, thereby further ensuring the safety of power use of the power equipment.

[0044] It will be understood from the following description that the technical solution of the embodiment of the present disclosure can respond quickly to disable the driver of the rectifier bridge when overcurrent / overvoltage occurs in the power equipment, thereby protecting the inverter and the load from damage and enhancing the safety of the equipment.

[0045] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the disclosure, nor is it intended to limit the scope of the disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 A circuit diagram of an inverter according to an embodiment of the present disclosure is shown;

[0047] Figure 2 A schematic diagram showing an overcurrent protection circuit of an inverter according to some exemplary embodiments of the present disclosure is shown;

[0048] Figure 3 A schematic diagram of a logic circuit for controlling a driver of an inverter according to some exemplary embodiments of the present disclosure is shown;

[0049] Figure 4 A flow chart of an overcurrent protection method according to some exemplary embodiments of the present disclosure is shown;

[0050] Figure 5 A schematic diagram of related waveforms of an inverter additionally adopting a fixed current threshold according to an embodiment of the present disclosure and a schematic diagram of related waveforms of an inverter with a dynamic current threshold are shown;

[0051] Figure 6 A schematic diagram showing a curve showing the relationship between dynamic threshold current and output voltage according to some exemplary embodiments of the present disclosure

[0052] Figure 7 A screenshot showing relevant test waveforms of an inverter according to some exemplary embodiments of the present disclosure; and

[0053] Figure 8 A schematic diagram of a curve showing the temperature rise of a MOSFET in a driver in an inverter according to some exemplary embodiments of the present disclosure is shown.

[0054] In the various drawings, the same or corresponding reference numerals represent the same or corresponding parts. DETAILED DESCRIPTION

[0055] The principles of the present disclosure will be described below with reference to the various exemplary embodiments shown in the accompanying drawings. It should be understood that the description of these embodiments is only to enable those skilled in the art to better understand and further implement the present disclosure, and is not intended to limit the scope of the present disclosure in any way. It should be noted that similar or identical reference numerals may be used in the figures where feasible, and similar or identical reference numerals may represent similar or identical functions. Those skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods described herein may be adopted without departing from the principles of the present invention described herein.

[0056] As used herein, the term "including" and its variations mean open inclusion, i.e., "including but not limited to". Unless otherwise stated, the term "or" means "and / or". The term "based on" means "based at least in part on". The terms "an example embodiment" and "an embodiment" mean "at least one example embodiment". The term "another embodiment" means "at least one additional embodiment". The terms "first", "second", etc. may refer to different or the same objects.

[0057] As mentioned above, a fixed overcurrent protection threshold is usually set in traditional overcurrent protection schemes. However, the overcurrent protection response time may be different under different voltage and current outputs. For example, when a short circuit or overload occurs at a higher output voltage, the response time of the protection device is slower, resulting in the risk of damage to the inverter or load.

[0058] In the traditional scheme, a constant current threshold is usually set for the comparator. The current threshold will be set to the upper limit of all conditions, which can usually be determined by the relevant parameters of the sampling device. However, the inverter output voltage usually ranges from 108Vrms to 277Vrms, and the maximum current will be 1.5 times the minimum current, which results in a longer response time for protection when a short circuit or overload occurs at a higher output voltage. This will damage the reliability of the semiconductor device because the final peak current may be significantly greater than the acceptable value of the semiconductor device. In addition, in the traditional scheme, a smaller propagation delay is required in the relevant devices in the protection circuit in order to control the further generation of the pulse width modulation (PWM) signal of the driver in a timely manner. This increases the design difficulty of the current sampling circuit. In addition, it is known that the traditional scheme uses an inductor with a larger inductance to limit the rise speed of the current. Although this helps to reduce the requirements for the response time of the overcurrent protection, this leads to more copper loss in the inductor.

[0059] In addition, the inverter provides power to various types of loads at different voltage outputs. RCD (resistor, capacitor, diode) loads usually have a large crest factor and are prone to accidentally triggering the over current protection (OCP). Due to low power factor, the current may lead or lag the voltage, so the OCP threshold should be adjusted to accommodate the actual power factor value and the root mean square (RMS) voltage of the output.

[0060] Furthermore, conventional solutions usually select field effect transistors with larger rated currents to sustain high pulsating currents during transients, which ultimately increases costs.

[0061] Therefore, an improved solution is urgently needed to increase the response speed of overcurrent protection, so as to provide accurate protection for different output conditions, thereby enhancing the safety of the device.

[0062] Embodiments of the present disclosure provide an improved power device with an overcurrent protection function. The power device includes: a rectifier bridge, a first voltage sensor, a current sensor, a threshold current setting unit, and a control unit. The rectifier bridge is configured to rectify an input voltage to output a rectified voltage. The rectifier bridge can rectify a DC input voltage to an AC output voltage, or it can rectify an AC input voltage to a DC output voltage. The first voltage sensor is configured to generate a first voltage signal indicating the magnitude of one of the input voltage or the rectified voltage. The first voltage sensor can be, for example, any component capable of sensing voltage, such as a resistor divider. The current sensor is configured to generate a current signal indicating the magnitude of the output current of the rectifier bridge. The current sensor can be, for example, any component capable of sensing current, such as a current transformer. The threshold current setting unit is configured to dynamically determine a threshold current based on the first voltage signal. The control unit is configured to generate a control signal in response to the current signal exceeding the threshold current to disable the driver of the rectifier bridge. In this way, by setting a dynamic current threshold based on the first voltage signal, when the output current exceeds the threshold, the control unit can respond quickly, so that the driver of the rectifier bridge stops outputting, thereby protecting the inverter and the load from damage caused by overcurrent. This solution can provide accurate protection for different output conditions and enhance the safety of the equipment.

[0063] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Figure 1 FIG. 1 is a circuit diagram of an inverter 100 according to an embodiment of the present disclosure.

[0064] like Figure 1 As shown, the inverter includes a rectifier bridge 110, an inductor L1, a first capacitor C1, a second capacitor C2, an input voltage sensor VS1, a rectified voltage sensor VS2, and a current sensor CS.

[0065] The rectifier bridge 110 can rectify the input voltage to output a rectified voltage. Figure 1 As shown, the rectifier bridge 110 includes a first bridge arm and a second bridge arm. The first bridge arm includes a first controllable switch Q1 and a second controllable switch Q2 connected in series to a first node A. The second bridge arm includes a third controllable switch Q3 and a fourth controllable switch Q4 connected in series to a second node B, wherein two ends of the second bridge arm and two ends of the first bridge arm are connected in parallel to a third node D and a fourth node E, respectively.

[0066] In some embodiments, the first controllable switch Q1 and the second controllable switch Q2 may be high-frequency switching devices. For example, a high-frequency metal-oxide-semiconductor field-effect transistor (MOSFET). The third controllable switch Q3 and the fourth controllable switch Q4 may be power frequency switching devices, such as power frequency MOSFETs. The operating frequency of the first controllable switch Q1 and the second controllable switch Q2 may be 20 to 1000 times the operating frequency of the third controllable switch Q3 and the fourth controllable switch Q4. The MOSFET mentioned here is only a schematic description of the scheme of the embodiment of the present disclosure, and the embodiment of the present disclosure is not limited thereto, and a variety of devices can implement the scheme of the present disclosure. In addition, the operating frequency of each controllable switch is not limited to the range mentioned above.

[0067] When a high level exceeding the conduction voltage is applied to the control terminal of each of the first controllable switch Q1, the second controllable switch Q2, the third controllable switch Q3 and the fourth controllable switch Q4, the corresponding controllable switch is turned on. For example, when the first controllable switch Q1 and the fourth controllable switch Q4 are turned on, the current flows to the fourth node E via the third node D, the first controllable switch Q1, the inductor L1, the resistor R1, and the fourth controllable switch Q4, that is, positive modulation is achieved. Similarly, when the second controllable switch Q2 and the third controllable switch Q3 are turned on, the current flows in the direction opposite to the aforementioned direction, that is, negative modulation is achieved. Thus, a sine wave is output on the output side. In this way, a desired sinusoidal waveform can be obtained on the output side of the rectifier bridge 110.

[0068] In the above embodiment, the inverter 100 is a totem pole structure including two bridge arms. The embodiments of the present disclosure are not limited thereto, and the inverter of the present disclosure may also include only one bridge arm to implement unipolar modulation. In a conventional totem pole inverter, the power frequency switch usually performs AC zero-crossing switching, and the high frequency switch performs PWM modulation, which is not described in detail herein.

[0069] The second capacitor C2 is connected in parallel with the first bridge arm and the second bridge arm, and is configured to smooth the voltage of the previous stage rectification (not shown in the figure) to output an input voltage for inputting the inverter.

[0070] like Figure 1 As shown, the first end of the inductor L1 is coupled to the first node A; the first end of the first capacitor C1 is coupled to the second end of the inductor L1, and the second end of the first capacitor C1 is coupled to the fourth node E, wherein the two ends of the first capacitor C1 are suitable for connecting the load in parallel. The two ends of the second capacitor C2 are respectively coupled between the third node D and the fourth node E, wherein the input voltage is applied between the third node D and the fourth node E.

[0071] The current sensor CS can sense the current flowing through the inductor L1 to generate a current signal Iinv indicating the magnitude of the rectified current output by the rectifier bridge 110. The current sensor CS can be a Hall sensor or a current transformer. The embodiments of the present disclosure are not limited thereto, but can be any device capable of sensing current.

[0072] In some embodiments, Figure 1 As shown, the inverter 100 includes an input voltage sensor VS1 and a rectifier voltage sensor VS2. The input voltage sensor VS1 can sense the voltage across the second capacitor C2 to generate an input voltage signal Vpfc indicating the magnitude of the input voltage. The voltage across the second capacitor C2 is theoretically a DC voltage, but in reality it is superimposed with an AC component, wherein the AC component is usually about plus or minus 50 volts. That is, the voltage across the second capacitor C2 is a fluctuating voltage.

[0073] The rectified voltage sensor VS2 can sense the voltage across the first capacitor C1 to generate a rectified voltage signal Vinv indicating the magnitude of the rectified voltage. In some embodiments, the rectified voltage sensor VS2 can sense the root mean square value of the voltage across the first capacitor C1 to generate the rectified voltage signal Vinv. In some embodiments, the instantaneous value of the voltage across the first capacitor C1 can also be sensed by the rectified voltage sensor VS2, and the root mean square value can be calculated in the processor based on the sensing result, which is further described below.

[0074] exist Figure 1 , the input voltage sensor VS1 and the rectifier voltage sensor VS2 are shown at the same time. The embodiments of the present disclosure are not limited thereto. In some other embodiments, the inverter 100 may include only one of the input voltage sensor VS1 and the rectifier voltage sensor VS2. That is, in some other embodiments, only the input voltage or only the output voltage may be sensed. Then, the current threshold may be determined based on the sensed input voltage or the sensed output voltage.

[0075] Figure 1 In the illustrated embodiment, the resistor R1 is a load connected to the output terminal of the inverter 100. The embodiments of the present disclosure are not limited thereto, and in addition to the resistor, the load may also be any other type of load, such as a capacitive or inductive load.

[0076] In some embodiments of the present disclosure, a dynamic current threshold can be determined by sensing the input voltage and / or output voltage of the inverter 100, so that overcurrent protection can be implemented based on this.

[0077] Combine the following Figure 2 An overcurrent protection circuit according to some embodiments of the present disclosure is described. Figure 2A schematic diagram of an overcurrent protection circuit of an inverter according to some exemplary embodiments of the present disclosure is shown.

[0078] Figure 2 The Iinv shown is from Figure 1 The current signal Iinv is from Figure 1 The rectified voltage signal Vinv of the rectified voltage sensor VS2; Vpfc is from Figure 1 The input voltage signal Vpfc of the input voltage sensor VS1.

[0079] like Figure 2 As shown, the overcurrent protection circuit mainly includes a sampling unit 102 , a threshold current setting unit 130 , a control unit 150 , a constant overcurrent protection unit 140 , and a constant overvoltage protection unit 124 .

[0080] The threshold current setting unit 130 may dynamically determine the threshold current based on the input voltage signal Vpfc and / or the rectified voltage signal Vinv. Figure 2 As shown, the threshold current setting unit 130 includes an analog-to-digital converter (ADC) 104 and a processor 112. The analog-to-digital converter 104 can sample and analog-to-digital convert the input voltage signal Vpfc and the rectified voltage signal Vinv, respectively, to generate a first digital voltage signal S-1 and a second digital voltage signal S-2, respectively. The processor 112 can generate a threshold current based on the first digital voltage signal S-1 and the second digital voltage signal S-2. The processor 112 can be, for example, a microcontroller unit (MCU). The embodiments of the present disclosure are not limited thereto, but can also be any device having a computing function.

[0081] The following further describes how the processor 112 generates a threshold current based on the first digital voltage signal S- 1 and the second digital voltage signal S- 2 according to some embodiments of the present disclosure.

[0082] The input voltage mentioned above is also called bus voltage or power factor correction (PFC) voltage, which is sampled together with the output voltage of the inverter 100 or separately (respectively marked as V pfc and V inv ), and then sent to the processor 112 for processing to determine the threshold current. Different output voltages require different bus voltages to modulate the waveform. In order to maintain a sinusoidal waveform, the bus voltage can be set by the following formula:

[0083]

[0084] Wherein a1 may be, for example, greater than or equal to 20 V and less than or equal to 50 V. The embodiments of the present disclosure are not limited thereto and can be adjusted according to actual needs.

[0085] When the output of the inverter 100 is short-circuited, the instantaneous peak current change can be determined by the following formula:

[0086]

[0087] Where Td represents the delay.

[0088] The expected short-circuit peak current is:

[0089]

[0090] Where Z load is the load impedance; K crest_factor is the peak factor. Assuming it is a pure resistive load, K crest_factor =1. V inv_rms It represents the RMS value of the rectified output voltage. f is the power frequency, and θ is the phase difference between the output voltage and the output current.

[0091] Theoretically, the peak current will occur at =π / 2, when the current is at its maximum value. A certain margin can be left according to the needs of the actual application, such as a 20% margin. Given the inverter output root mean square (RMS) voltage V inv_rms The peak current is set to:

[0092]

[0093]

[0094] Among them, P load is the active power; assuming the load is a pure resistance load, Z load =R load , P load =V 2 / R load , where R load Represents the impedance of a pure resistor. L is the inductance of an inductor.

[0095] Wherein a2 may be, for example, greater than or equal to 50 and less than 80. The embodiments of the present disclosure are not limited thereto and may be adjusted according to actual needs.

[0096] Therefore I max_set is the absolute maximum current of the resistive load. This value can be set to an upper limit value related to the effective value voltage output by the inverter 100. That is, if a constant current threshold is set, the constant current threshold can be set to I max_setFor dynamic voltage waveforms, the overcurrent protection threshold current can be set as a real-time function of the voltage waveform (resistive load) and updated at every switching cycle.

[0097]

[0098] In some embodiments, in order to ensure the safety of the bus voltage, overvoltage protection of the bus voltage should be considered. The overcurrent protection threshold current can be determined by the following formula:

[0099]

[0100] Wherein a2, as mentioned above, may be greater than or equal to 50 and less than 80. set (t) will be generated as a waveform sent to the digital-to-analog converter and used as one of the inputs to the comparator. As mentioned above, Td represents the delay, which depends on the ADC 104, the processor 112 and the driver 302 (see Figure 3 ) and other delays.

[0101] As shown in formula (7), when the amplitude of the input voltage signal Vpfc is less than the amplitude of the rectified voltage signal Vinv, When the threshold current is equal to the sum of a2 and a2, the threshold current is the first equation in formula (7). Otherwise, the threshold current is the second equation in formula (7).

[0102] By setting different current thresholds according to different input voltage signals Vpfc, the safety performance of the inverter can be improved.

[0103] It can be seen from the formula of the above embodiment that the threshold current may be related to one or more of the following parameters:

[0104] The rms value of the rectified voltage V inv_rms ;

[0105] The phase difference between the rectified current and the rectified voltage;

[0106] Active power of load P load ;

[0107] Processing delay of input voltage signal Vpfc and output voltage signal Vinv;

[0108] the inductance of the inductor; and

[0109] Delay of the driver of the rectifier bridge.

[0110] In the embodiments of the present disclosure, the above formulas are used as examples to illustrate the method of calculating the threshold current. The embodiments of the present disclosure are not limited thereto, but may be varied as needed. For example, in some embodiments, the threshold current may be determined based only on the input voltage or the output rectified voltage. In this case, the term related to the input voltage or the term related to the output rectified voltage in the formula may be regarded as a fixed value, and the calculation may be performed on this basis, thereby simplifying the calculation process and improving the response speed.

[0111] For different output scenarios, the threshold current can be updated in each PWM cycle of the driver, thereby more accurately controlling the current threshold, or the envelope of the current output limit.

[0112] pass Figure 2 It can be seen that in some embodiments of the present disclosure, the conventional fixed threshold current / voltage protection methods are retained as additional protection. These protection methods can be combined with any logic of programmable threshold current.

[0113] Continue to refer to Figure 2 The sampling unit 102 can sample and convert the current signal Iinv into current / voltage, and output a first conversion voltage signal CMP_P+ corresponding to the positive half cycle of the current signal Iinv and a second conversion voltage signal CMP_N+ corresponding to the negative half cycle of the current signal Iinv.

[0114] The control unit 150 may generate a control signal in response to the current signal Iinv exceeding the threshold current, and the control signal may cause the driver of the rectifier bridge 110 to stop outputting the drive signal. That is, the driver of the rectifier bridge 110 is disabled by the control signal. The control unit 150 includes a first digital-to-analog converter DAC1 and a second digital-to-analog converter DAC2. The first digital-to-analog converter DAC1 may convert the threshold current in the positive half cycle into a first analog threshold signal CMP_P-. The second digital-to-analog converter DAC2 may convert the threshold current in the negative half cycle into a second analog threshold signal CMP_N-.

[0115] The control unit 150 may further include a first comparator 114 and a second comparator 116. The first analog threshold signal CMP_P- and the second analog threshold signal CMP_N- are respectively input to the first comparator 114 and the second comparator 116 as a reference for judging overcurrent. The first comparator 114 may generate a first control signal S1 in response to the first conversion voltage signal CMP_P+ exceeding the first analog threshold signal CMP_P-. The second comparator 116 may output a second control signal S2 in response to the second conversion voltage signal CMP_N+ exceeding the second analog threshold signal CMP_N-. Either of the first control signal S1 and the second control signal S2 may be used as a control signal. This is achieved by a subsequent logic OR gate.

[0116] In some embodiments, the control unit 150 further includes a first filter 106 and a second filter 108. The first filter 106 may filter the first control signal S1 to generate a first filtered signal FOUT1. The second filter 108 may filter the second control signal S4 to generate a second filtered signal FOUT2.

[0117] If the signal interference in the circuit is greater than a predetermined value, it needs to be filtered by the first filter 150 to remove the interference signal and output a filtered signal FOUT1.

[0118] If the signal interference in the circuit is less than or equal to a predetermined value, filtering is not necessary, and the control unit 150 can directly output the unfiltered signal S1, thereby achieving a faster response speed.

[0119] In some embodiments, the inverter 100 further includes a constant overcurrent protection unit 140 and a constant overvoltage protection unit 124. The constant overcurrent protection unit 140 may output a third control signal S3 in response to the output current exceeding the constant threshold current. The constant overvoltage protection unit 124 may output a fourth control signal S4 in response to the input voltage exceeding the constant threshold voltage Vpro.

[0120] The constant overcurrent protection unit 140 and the constant overvoltage protection unit 124 can be used as alternative functional units together with the control unit 150. As long as the output current of the inverter 100 exceeds any one of the dynamic threshold current, the constant threshold voltage, and the constant threshold current, the protection function is triggered, and the driver of the rectifier bridge is disabled, so that the rectifier bridge no longer outputs.

[0121] Therefore, the third control signal S3 output by the constant overcurrent protection unit 140 and the fourth control signal S4 output by the constant overvoltage protection unit 124 can be selectively used to disable the driver of the rectifier bridge 110 , respectively.

[0122] like Figure 3As shown, the constant overcurrent protection unit 150 includes a third comparator 118 and a fourth comparator 120. The third comparator 118 may output a fifth control signal S5 in response to the first conversion voltage signal CMP_P+ exceeding the first constant threshold voltage signal CMP1_P- converted by the first constant threshold current signal Con1 in the constant threshold current. The fourth comparator 120 may output a sixth control signal S6 in response to the second conversion voltage signal CMP_N+ exceeding the second constant threshold voltage signal converted by the second constant threshold current signal Con2 in the constant threshold current. The first OR gate 122 may perform a logical OR operation on the fifth control signal S5 and the sixth control signal S6 to generate a third control signal S3.

[0123] In some embodiments, the sampling unit 102 may be an analog-to-digital converter (ADC). The ADC may have isolation and filtering functions, and may isolate and filter the input surge current.

[0124] Figure 2 The Vpro in the figure is a constant threshold voltage signal. The input voltage signal Vpfc output by the input voltage sensor VS1 is compared with the constant threshold voltage signal Vpro. When the input voltage signal Vpfc exceeds the constant threshold voltage signal Vpro, the fifth comparator 124 outputs a high level signal, i.e., the fourth control signal S4. The fourth control signal S4 can be used together with the control signal generated by the control unit 150 to control the working state of the driver of the rectifier bridge 110. Figure 3 This is further described.

[0125] Figure 3 A schematic diagram of a logic circuit for controlling a driver of an inverter according to some exemplary embodiments of the present disclosure is shown.

[0126] In some embodiments, the inverter may further include a logic circuit 160 and a driver 302. The logic circuit 160 may perform a logic OR operation on the control signal generated by the control unit 150, the third control signal S3 generated by the constant overcurrent protection unit 140, and the fourth control signal S4 generated by the constant overvoltage protection unit 124 to output a high level signal as the control signal.

[0127] like Figure 3 As shown, the logic circuit 160 includes a second OR gate 126, a third OR gate 128, and a fourth OR gate 132. The signals S1, FOUT1, S2, and FOUT2 from the control unit 150 are input to the logic circuit 160, specifically to the second OR gate 126. A first input terminal of the second OR gate 126 is provided with a first switch K1, and a second input terminal is provided with a second switch K2.

[0128] The second OR gate 126 can perform a logical OR operation on the first input signal and the second input signal, wherein the first input signal is a signal selected from the first filter signal FOUT1 and the unfiltered first control signal S1; the second input signal is a signal selected from the second filter signal FOUT2 and the unfiltered second control signal S2. As mentioned above, it can be determined whether to perform filtering processing according to the actual signal interference in the circuit. The second OR gate 126 outputs the high-level signal of the first input signal and the second input signal as the seventh control signal S7. The third OR gate 128 performs a logical OR operation on the seventh control signal S7 and the third control signal S3, and outputs the high-level signal of the two as the eighth control signal S8. The fourth OR gate 132 performs a logical OR operation on the eighth control signal S8 and the fourth control signal S4, and outputs the high-level signal of the two as the ninth control signal S9.

[0129] Figure 3 Three logic OR gates are shown in FIG. 1 , but the embodiments of the present disclosure are not limited thereto, and may have various modifications. For example, one OR gate may be used to receive all input signals at the same time.

[0130] The driver 302 is used to output drive signals G1, G2, G3, G4 to drive the rectifier bridge 110. Specifically, the drive signals G1, G2, G3, G4 are used to drive the first controllable switch Q1, the second controllable switch Q2, the third controllable switch Q3 and the fourth controllable switch Q4 respectively. Figure 3 As shown, the driver 302 may stop outputting the driving signals G1 , G2 , G3 , and G4 for driving the respective controllable switches in the rectifier bridge 110 in response to receiving the control signal.

[0131] In the embodiment of the present disclosure, a dynamic or real-time programmable threshold current can be provided for the comparator, and the comparator generates a trigger signal to make the driver 302 stop outputting the PWM driving signal when over-current protection occurs.

[0132] In the embodiments of the present disclosure, Figures 1 to 3 The scheme of the present disclosure is described. The scheme of the present disclosure is not limited thereto, and the above specific circuit structure is illustrative and can be changed in various ways.

[0133] like Figure 3 , wherein a reset signal Reset is also shown. The reset signal Reset will be directly sent to the driver 302 with the highest priority. For example, after the overcurrent condition is eliminated, the reset signal Reset can be sent to the driver 302 to enable the driver 302 to resume driving.

[0134] Figure 4A flow chart of an overcurrent protection method for an electric power device according to some exemplary embodiments of the present disclosure is shown. The electric power device includes a rectifier bridge 110, and the rectifier bridge 110 is configured to rectify an input voltage to output a rectified voltage. The method includes:

[0135] At block 402 , a first voltage signal indicating a magnitude of a voltage is generated based on one of an input voltage or a rectified voltage.

[0136] At block 404 , a current signal Iinv indicating a magnitude of the output current is generated based on the output current of the rectifier bridge 110 .

[0137] At block 406, a threshold current is dynamically set based on the first voltage signal. In some embodiments, the first voltage signal and / or the second voltage signal may be sampled and analog-to-digital converted to generate a first digital voltage signal S-1 and / or a second digital voltage signal S-2, respectively; and the threshold current is generated based on the first digital voltage signal S-1 and / or the second digital voltage signal S-2.

[0138] At block 408 , a control signal is generated in response to the current signal Iinv exceeding a threshold current, the control signal may disable a driver of the rectifier bridge.

[0139] In some embodiments, the method further comprises: generating a second voltage signal indicating a magnitude of the other voltage based on the other voltage of the input voltage or the rectified voltage. The threshold current may then be dynamically determined based on the first voltage signal and / or the second voltage signal.

[0140] In some embodiments, the method further includes: sampling and current / voltage conversion of the current signal Iinv, and outputting a first conversion voltage signal CMP_P+ corresponding to the positive half cycle of the current signal Iinv and a second conversion voltage signal CMP_N+ corresponding to the negative half cycle of the current signal Iinv, respectively.

[0141] In some embodiments, the method further includes: converting the threshold current in the positive half cycle into a first analog threshold signal CMP_P-; converting the threshold current in the negative half cycle into a second analog threshold signal CMP_N-. When the first conversion voltage signal CMP_P+ exceeds the first analog threshold signal CMP_P-, a first control signal S1 is generated; or, when the second conversion voltage signal CMP_N+ exceeds the second analog threshold signal CMP_N-, a second control signal S2 is output; and any one of the first control signal S1 and the second control signal S2 is used as the control signal. Because the first control signal S1 and the second control signal S2 are signals corresponding to the positive half cycle and the negative half cycle respectively, the two will not appear at the same time. Therefore, when the first control signal S1 or the second control signal S2 of a high level appears, the driver of the rectifier bridge 110 is disabled.

[0142] In some embodiments, the control signal is output to disable the driver of the rectifier bridge 110 in any of the following cases:

[0143] The current signal Iinv exceeds the threshold current;

[0144] The output current exceeds a constant threshold current; and

[0145] The input voltage exceeds a constant threshold voltage Vpro.

[0146] Combine the following Figure 5 Schematic diagram of threshold current curve describing the scheme of the present disclosure. Figure 5 Schematic diagrams of relevant waveforms of an inverter additionally adopting a fixed current threshold according to an embodiment of the present disclosure and schematic diagrams of relevant waveforms of an inverter with a dynamic current threshold are shown.

[0147] Figure 5 In (A), the current thresholds use conventional fixed values, which are the constant positive threshold 502 and the constant negative threshold 508 shown in the figure. The output voltage 506 and the output current 504 are respectively as follows: Figure 5 As shown in (A).

[0148] Figure 5 In (B), the current threshold is a dynamic threshold, such as Figure 5 As shown in (B), the dynamic positive threshold 510 is a part of the positive cycle of the sinusoidal curve, and the dynamic negative threshold 514 is a part of the negative cycle of the sinusoidal curve. The output voltage 512 and the output current 516 are respectively as follows: Figure 5 As shown in (B).

[0149] Figure 6A curve diagram showing the relationship between dynamic threshold current and output voltage according to some exemplary embodiments of the present disclosure is shown.

[0150] In some embodiments of the present invention, three 3kW inverter prototypes are built to conduct experiments, and the experimental results verify the feasibility of short-circuit protection.

[0151] Experimental and theoretical analysis show that the peak short-circuit current is determined by the bus voltage level. In the prototype test, the delay of the threshold current signal processing of the overcurrent protection is 20-30ns, and the response time of the current transformer is 200ns. The total signal delay is 250ns. In this test, the inductance of the inductor in the inverter is 100uH.

[0152] Figure 6 In the figure, the horizontal axis represents the output voltage and the vertical axis represents the dynamic threshold current. Figure 6 As shown, the output current (i.e., dynamic threshold current) increases as the output voltage decreases to prevent the overcurrent protection (OCP) from being triggered by normal output current. The OCP set point has the following relationship to the output voltage setting (which can be obtained by substituting the relevant values ​​into the previous formula). By changing the output RMS value during operation, the threshold of the overcurrent protection will automatically adjust, for example according to the following formula:

[0153] locp=0.0015Vac2-0.7144Vinv+114.55

[0154] The Iocp here corresponds to the previous Iset, that is, the threshold current of the overcurrent protection.

[0155] Precise control of the overcurrent protection setting can significantly reduce current overshoot under various conditions and improve the reliability of semiconductor devices. Prototype testing shows that the short-circuit current remains below 101A. Considering the DC bias inductor saturation, this is within the acceptable range of the device.

[0156] In the previous embodiments, it is described that the dynamic threshold current can be determined by the input voltage and the output voltage. The embodiments of the present disclosure are not limited to this. For example, if the input voltage is a constant value, the threshold output current can be determined only by the output voltage. Similarly, if the output voltage is a constant value (or is regarded as a constant value), the threshold output current can be determined only by the input voltage. In addition, even if both the input voltage and the output voltage are not constant values, in order to simplify the calculation process, one of them (for example, one with small fluctuations) can be treated as a constant value, thereby determining the threshold current based only on the other voltage. By using the threshold current determined in this way, it still has a better overcurrent protection effect than the traditional scheme of setting a fixed value.

[0157] Figure 7Shown are screenshots of relevant test waveforms of an inverter according to some exemplary embodiments of the present disclosure.

[0158] The short-circuit test is performed at Vinv = 277 V, Vpfc = 400 V. The overshoot of the short-circuit current is determined by the bus voltage. Figure 7 In FIG. 7 , curve 702 is the inverter output voltage; curve 704 is the inverter output current; and curve 706 is the overcurrent protection signal, i.e., the control signal mentioned above, whose high level is about 3.3 volts. Figure 7 As shown, the peak current is 101A, and the overcurrent protection time is about 40us. Then the inverter 100 generates a constant short-circuit output current. It should be noted that Figure 7 The test environment is only illustrative, and similar tests can be performed in other test environments.

[0159] Figure 8 A schematic diagram of a curve showing the temperature rise of a MOSFET in a driver in an inverter according to some exemplary embodiments of the present disclosure is shown.

[0160] In the test, the output of the totem pole inverter was short-circuited for 20 seconds, and the MOSFET temperature rise was <60°C (temperature on the die) at an ambient temperature of 28°C. The temperature rise of all MOSFETs did not exceed the data sheet limit, so it met the expected design requirements. As mentioned above, the controllable switch in the inverter of the embodiment of the present disclosure is not limited to MOSFET. Other tests have shown that a variety of devices can implement the scheme of the present disclosure, meeting the expected design requirements.

[0161] The solution of the embodiment of the present disclosure has the following advantages:

[0162] 1) The reduction of overcurrent protection response time improves the thermal performance of the switching device and reduces the failure rate of the switching device.

[0163] 2) The propagation time requirements for sampling and isolation components are less stringent, allowing more precise control of current overshoot in each PWM cycle.

[0164] 3) The switching device will be subjected to a small pulsating current during the transient period.

[0165] 4) It is applicable to different inverters with various rated powers without changing the hardware design of the current sampling circuit.

[0166] 5) Reduce the overall cost of the entire inverter design and improve system efficiency.

[0167] 6) It can provide accurate protection for different output voltages and currents, improve the response speed of overcurrent protection, and enhance the safety of the inverter and load.

[0168] The above embodiments are described using an inverter as an example. It should be noted that the embodiments of the present disclosure are not limited to inverters, but can also be applied to any other device including a bridge circuit, for example, a device including a bridge rectifier circuit that utilizes a bridge circuit to rectify an AC voltage into a DC voltage.

[0169] Various embodiments of the present disclosure have been described above, and the above descriptions are exemplary and are only optional embodiments of the present disclosure, not exhaustive, and are not intended to limit the present disclosure. Although the claims in this application have been formulated for specific combinations of features, it should be understood that the scope of the present disclosure also includes any novel features or any novel combination of features disclosed herein, whether or not it relates to the same scheme in any claim currently claimed for protection. The applicant hereby informs that new claims may be formulated into these features and / or combinations of these features during the examination of this application or in any further application derived therefrom.

[0170] The terms used in this article are selected to best explain the principles of each embodiment, practical application or technical improvement in the market, or to enable other ordinary technicians in the field to understand the embodiments disclosed herein. For those skilled in the art, the present disclosure may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present disclosure shall be included in the scope of protection of the present disclosure.

Claims

1. An electric power device (100), comprising: A rectifier bridge (110) configured to rectify an input voltage to output a rectified voltage; a first voltage sensor configured to generate a first voltage signal indicating a magnitude of one of the input voltage or the rectified voltage; A current sensor (CS) configured to generate a current signal (Iinv) indicating the magnitude of the output current of the rectifier bridge (110); A threshold current setting unit (130) configured to dynamically determine a threshold current based on the first voltage signal; as well as A control unit (150) is configured to generate a control signal to disable a driver of the rectifier bridge (110) in response to the current signal (Iinv) exceeding the threshold current.

2. The power device (100) according to claim 1, further comprising: a second voltage sensor configured to generate a second voltage signal indicative of a magnitude of the other of the input voltage or the rectified voltage; The threshold current setting unit (130) is configured to dynamically determine the threshold current based on at least one of the first voltage signal or the second voltage signal.

3. The power device (100) according to claim 2, wherein the threshold current setting unit (130) comprises: an analog-to-digital converter (104), configured to sample and perform analog-to-digital conversion on the first voltage signal and / or the second voltage signal, respectively, to generate a first digital voltage signal (S-1) and / or a second digital voltage signal (S-2), respectively; as well as A processor (112) is configured to generate the threshold current based on the first digital voltage signal (S-1) and / or the second digital voltage signal (S-2).

4. The power device (100) according to claim 2, further comprising: The sampling unit (102) is configured to sample and perform current / voltage conversion on the current signal (Iinv), and output a first conversion voltage signal (CMP_P+) corresponding to a positive half cycle of the current signal (Iinv) and a second conversion voltage signal (CMP_N+) corresponding to a negative half cycle of the current signal (Iinv).

5. The power device (100) according to claim 4, wherein the control unit (150) comprises: a first digital-to-analog converter (DAC1) configured to convert the threshold current in the positive half cycle into a first analog threshold signal (CMP_P-); as well as The second digital-to-analog converter (DAC2) is configured to convert the threshold current in the negative half cycle into a second analog threshold signal (CMP_N-).

6. The power device (100) according to claim 5, wherein the control unit (150) further comprises: a first comparator (114) configured to generate a first control signal (S1) in response to the first conversion voltage signal (CMP_P+) exceeding the first analog threshold signal (CMP_P-); and a second comparator (116) configured to output a second control signal (S2) in response to the second conversion voltage signal (CMP_N+) exceeding the second analog threshold signal (CMP_N-); Wherein, any one of the first control signal (S1) and the second control signal (S2) is used as the control signal.

7. The power device (100) according to claim 6, wherein the control unit (150) further comprises: A first filter (106) configured to filter the first control signal (S1) to generate a first filtered signal (FOUT1); as well as The second filter (108) is configured to filter the second control signal (S4) to generate a second filtered signal (FOUT2).

8. The power device (100) according to claim 7, further comprising: a constant overcurrent protection unit (140), configured to output a third control signal (S3) in response to the output current exceeding a constant threshold current; and / or A constant overvoltage protection unit (124) configured to output a fourth control signal (S4) in response to the input voltage exceeding a constant threshold voltage (Vpro) The third control signal (S3) and the fourth control signal (S4) are respectively selectively used to disable the driver of the rectifier bridge (110).

9. The power device (100) according to claim 8, wherein the constant overcurrent protection unit (150) comprises: a third comparator (118) configured to output a fifth control signal (S5) in response to the first conversion voltage signal (CMP_P+) exceeding the first constant threshold voltage signal (CMP1_P-) converted from the first constant threshold current signal (Con1) in the constant threshold current; a fourth comparator (120) configured to output a sixth control signal (S6) in response to the second conversion voltage signal (CMP_N+) exceeding the second constant threshold voltage signal converted by the second constant threshold current signal (Con2) in the constant threshold current; and The first OR gate (122) is configured to perform a logic OR operation on the fifth control signal (S5) and the sixth control signal (S6) to generate the third control signal (S3).

10. The power device (100) according to claim 9, further comprising: a logic circuit (160) configured to perform a logic OR operation on the control signal generated by the control unit (150), the third control signal (S3) generated by the constant overcurrent protection unit (140), and the fourth control signal (S4) generated by the constant overvoltage protection unit (124), so as to output a high-level signal as the control signal; and The driver (402) is configured to stop outputting a driving signal (G1, G2, G3, G4) for driving the rectifier bridge (110) in response to receiving the control signal.

11. The power device (100) according to claim 10, wherein the logic circuit (160) comprises: The second OR gate (126) is configured to perform a logical OR operation on a first input signal and a second input signal, wherein the first input signal is a signal selected from one of the first filtered signal (FOUT1) and the first control signal (S1) that has not been filtered; and the second input signal is a signal selected from one of the second filtered signal (FOUT2) and the second control signal (S2) that has not been filtered.

12. The power device (100) according to claim 2, wherein the rectifier bridge (110) comprises: A first bridge arm, comprising a first controllable switch (Q1) and a second controllable switch (Q2) connected in series to a first node (A); as well as The second bridge arm includes a third controllable switch (Q3) and a fourth controllable switch (Q4) connected in series to the second node (B), wherein the two ends of the second bridge arm and the two ends of the first bridge arm are respectively connected in parallel to the third node (D) and the fourth node (E).

13. The power device (100) according to claim 12, wherein the device (100) further comprises: an inductor (L1), wherein a first end of the inductor (L1) is coupled to the first node (A); a first capacitor (C1), wherein a first end of the first capacitor (C1) is coupled to a second end of the inductor (L1), and a second end of the first capacitor (C1) is coupled to the fourth node (E), wherein both ends of the first capacitor (C1) are suitable for being connected in parallel with a load; as well as A second capacitor (C2), wherein both ends of the second capacitor (C2) are respectively coupled between the third node (D) and the fourth node (E), wherein the input voltage is applied between the third node (D) and the fourth node (E).

14. The power device (100) according to claim 13, wherein: The current sensor (CS) is configured to sense the current flowing through the inductor (L1) to generate the current signal (Iinv); The first voltage sensor is configured to sense a voltage across the second capacitor (C2) to generate the first voltage signal; as well as The second voltage sensor is configured to sense a root mean square value of a voltage across the first capacitor (C1) to generate the second voltage signal.

15. An overcurrent protection method for an electric power device, the electric power device comprising a rectifier bridge (110), the rectifier bridge (110) being configured to rectify an input voltage to output a rectified voltage, the method comprising: Based on one of the input voltage or the rectified voltage, generating a first voltage signal indicating a magnitude of the one voltage; generating a current signal (Iinv) indicating the magnitude of the output current based on the output current of the rectifier bridge (110); dynamically setting a threshold current based on the first voltage signal; as well as A control signal is generated in response to the current signal (Iinv) exceeding the threshold current to disable a driver of the rectifier bridge (110).

16. The method according to claim 15, further comprising: generating a second voltage signal indicating a magnitude of the other voltage based on the other voltage of the input voltage or the rectified voltage; The threshold current is dynamically determined based on at least one of the first voltage signal or the second voltage signal.

17. The method of claim 16, wherein dynamically setting a threshold current based on the first voltage signal and / or the second voltage signal comprises: Sampling and analog-to-digital converting the first voltage signal and / or the second voltage signal respectively to generate a first digital voltage signal (S-1) and / or a second digital voltage signal (S-2); and The threshold current is generated based on the first digital voltage signal (S-1) and / or the second digital voltage signal (S-2).

18. The method according to claim 16, further comprising: The current signal (Iinv) is sampled and current / voltage converted, and a first conversion voltage signal (CMP_P+) corresponding to the positive half cycle of the current signal (Iinv) and a second conversion voltage signal (CMP_N+) corresponding to the negative half cycle of the current signal (Iinv) are output respectively.

19. The method according to claim 18, further comprising: Converting the threshold current in the positive half cycle into a first analog threshold signal (CMP_P-); Converting the threshold current in the negative half cycle into a second analog threshold signal (CMP_N-); generating a first control signal (S1) in response to the first conversion voltage signal (CMP_P+) exceeding the first analog threshold signal (CMP_P-); or outputting a second control signal (S2) in response to the second conversion voltage signal (CMP_N+) exceeding the second analog threshold signal (CMP_N-); and Any one of the first control signal (S1) and the second control signal (S2) is used as the control signal to disable the driver of the rectifier bridge (110).

20. The method according to claim 17, wherein: In any of the following cases, the control signal is output to disable the driver of the rectifier bridge (110): The current signal (Iinv) exceeds the threshold current; The output current exceeds a constant threshold current; and The input voltage exceeds a constant threshold voltage (Vpro).

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