H-bridge driving protection circuit and power equipment

Abstract

The invention relates to the technical field of circuit protection, in particular to an H-bridge driving protection circuit and power equipment. The circuit comprises a driving module which is used for driving and controlling the working state of each switch tube of the H-bridge circuit; the current anomaly detection module is used for detecting the output current of the load end in real time, judging whether the output current is abnormal or not and outputting a current judgment result; the voltage anomaly detection module is used for monitoring the change of the input voltage of the H-bridge circuit in real time, judging whether the input voltage is abnormal or not and outputting a voltage judgment result; and the signal processing module is connected with the current anomaly detection module and the voltage anomaly detection module, and adjusts the working state of the driving module based on the current judgment result and the voltage judgment result. According to the invention, monitoring in a wide current range can be realized without using a device with a large size and a large weight, abnormal large current protection is carried out, the power loss and the cost are low, and miniaturization of applied power equipment is facilitated.

Description

Technical Field

[0001] The present invention relates to the technical field of circuit protection, and particularly to an H-bridge drive protection circuit and a power device. Background Art

[0002] In modern power devices such as industrial frequency inverters, high-frequency inverters, and switching power supplies, H-bridge circuits are widely used in bidirectional DC / AC and AC / DC voltage conversions. The H-bridge circuit realizes precise regulation of load current and voltage by controlling the switching states of each switching tube. During the actual operation of the device, if the duty cycle of the switching tube is too large, the driving signal is abnormal, or a foreign object causes mis-conduction of the switching tube and other faults, the switching tube will bear an excessive current. Once the current exceeds the maximum rated value of the switching tube, it may cause damage or burnout of the switching tube, and in severe cases, it will lead to a complete failure of the device.

[0003] The traditional method for monitoring abnormally large current is to use a current sensor and a Hall sensor to detect the input current of the H-bridge circuit. Although it can provide relatively accurate current measurement, the detection of abnormally large current often requires devices with high power loss, large volume, and large weight. For example, a current sensor with a larger volume is needed, the circuit is more complex, the cost is higher, and it is not conducive to the miniaturization of the device. Summary of the Invention

[0004] The technical problem to be solved by the embodiments of the present invention is to provide an H-bridge drive protection circuit and a power device to solve the problems in the prior art that the monitoring method for abnormally large current in the H-bridge circuit has high power loss, high cost, and is not conducive to the miniaturization of the device.

[0005] The present invention discloses an H-bridge drive protection circuit for driving and protecting an H-bridge circuit. The voltage input terminal of the H-bridge circuit is connected to an input power supply, the voltage output terminal is connected to the primary side of a transformer, and the secondary side of the transformer is connected to a load terminal. The H-bridge drive protection circuit includes:

[0006] A drive module for driving and controlling the working states of each switching tube of the H-bridge circuit;

[0007] A current anomaly detection module for real-time detecting the output current of the load terminal and determining whether the output current is abnormal, and outputting a current determination result;

[0008] A voltage anomaly detection module for real-time monitoring the change of the input voltage of the H-bridge circuit and determining whether the input voltage is abnormal, and outputting a voltage determination result;

[0009] A signal processing module connected to the current anomaly detection module and the voltage anomaly detection module, and adjusting the working state of the drive module based on the current determination result and the voltage determination result.

[0010] Optionally, the voltage anomaly detection module includes a first comparator and a capacitor. The non-inverting input terminal of the first comparator is connected to the voltage input terminal of the H-bridge circuit and the first terminal of the capacitor, the inverting input terminal is connected to the voltage input terminal of the H-bridge circuit, the output terminal of the first comparator is connected to the first input terminal of the signal processing module, and the second terminal of the capacitor is grounded. The capacitor is used to store the input voltage of the H-bridge circuit and use it as the voltage reference value of the previous moment.

[0011] Optionally, the voltage anomaly detection module further includes a first resistor and a second resistor. The first resistor is connected in series between the voltage input terminal of the H-bridge circuit and the first terminal of the capacitor, and the second resistor is connected in series between the voltage input terminal of the H-bridge circuit and the inverting input terminal of the first comparator.

[0012] Optionally, the voltage anomaly detection module further includes a diode provided between the voltage input terminal of the H-bridge circuit and the first resistor. The positive electrode of the diode is connected to the voltage input terminal of the H-bridge circuit, and the negative electrode is connected to one end of the first resistor.

[0013] Optionally, the current anomaly detection module includes a current sampling unit, a second comparator, a third comparator, and a third resistor. The current sampling unit is used to collect the output current of the load end and convert it into a corresponding voltage signal. The inverting input terminal of the second comparator and the non-inverting input terminal of the third comparator are both connected to the output terminal of the current sampling unit. The non-inverting input terminal of the second comparator is used to input a first reference voltage, and the inverting input terminal of the third comparator is used to input a second reference voltage. The output terminals of the second comparator and the third comparator are both connected to the first end of the third resistor and the second input terminal of the signal processing module, and the second end of the third resistor is connected to an external power supply.

[0014] Optionally, the current sampling unit includes a current transformer, a fourth resistor, and an operational amplifier circuit. The two ends of the primary winding of the current transformer are respectively connected to the different-named terminals of the secondary side of the transformer and the load end, and the two ends of the secondary winding are respectively connected to the two ends of the fourth resistor and the two input terminals of the operational amplifier circuit. The fourth resistor is connected in parallel between the two input terminals of the operational amplifier circuit.

[0015] Optionally, the operational amplifier circuit includes an operational amplifier, a fifth resistor, a sixth resistor, and a seventh resistor. The fifth resistor is connected in series between the first end of the fourth resistor and the non-inverting input terminal of the operational amplifier, the sixth resistor is connected in series between the second end of the first resistor and the inverting input terminal of the operational amplifier, the seventh resistor is connected in series between the output terminal of the operational amplifier and the inverting input terminal, and the fourth resistor is connected in parallel between the two input terminals of the operational amplifier.

[0016] Optionally, the signal processing module includes an AND gate. The first input terminal of the AND gate is connected to the output terminal of the first comparator, the second input terminal is connected to the output terminals of the second comparator and the third comparator, and the output terminal of the AND gate is connected to the driving module.

[0017] Optionally, the driving module includes a single-chip microcomputer and a driving chip. The single-chip microcomputer is connected to the signal input terminal of the driving chip, and the enable terminal of the driving chip is connected to the signal processing module.

[0018] The present invention also discloses a power device, including an H-bridge circuit, a transformer, and the H-bridge driving and protecting circuit as described above. The voltage input terminal of the H-bridge circuit is connected to an input power supply, the voltage output terminal is connected to the primary side of the transformer, the secondary side of the transformer is connected to a load terminal, the driving module of the H-bridge driving and protecting circuit is used to drive and control the working states of the switching tubes of the H-bridge circuit, the current anomaly detection module is used to detect the output current of the load terminal and determine whether the output current is abnormal, and output a current judgment result, and the voltage anomaly detection module is used to monitor the change of the input voltage of the H-bridge circuit in real time and determine whether the input voltage is abnormal, and output a voltage judgment result.

[0019] Compared with the prior art, the beneficial effects of the H-bridge driving and protecting circuit and the power device provided by the embodiments of the present invention are as follows: By setting a current anomaly detection module to detect the output current of the load terminal in real time and determine whether the output current is abnormal, and a voltage anomaly detection module to monitor the change of the input voltage of the H-bridge circuit in real time and determine whether the input voltage is abnormal, indirectly judge whether the switching tubes of the H-bridge circuit are transmitting a large current, without directly collecting the input current of the H-bridge circuit, having a wide current monitoring range, and cooperating with the abnormal situation of the output current of the load terminal detected by the current anomaly detection module to control and adjust the working state of the driving module, can drive and control to disconnect the switching tubes of the H-bridge circuit when an abnormal large current appears, realizing abnormal large current protection. Therefore, the present application can monitor a wide current range and perform abnormal large current protection without using devices with a large volume and a large weight, with low power loss and cost, and is beneficial to the miniaturization of the applied power device. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The technical solutions of the present invention will be further described in detail below with reference to the drawings and embodiments. In the drawings:

[0021] Figure 1 is a structural block diagram of the H-bridge driving and protecting circuit provided by an embodiment of the present invention;

[0022] Figure 2 is a partial circuit schematic diagram of the H-bridge driving and protecting circuit provided by an embodiment of the present invention.

[0023] The reference numerals in the figures are as follows:

[0024] 100, H-bridge circuit; Q1, first switching transistor; Q2, second switching transistor; Q3, third switching transistor; Q4, fourth switching transistor; T1, transformer;

[0025] 200, H-bridge drive protection circuit;

[0026] 210, drive module; 220, current anomaly detection module; 221, current sampling unit; 230, voltage anomaly detection module; 240, signal processing module;

[0027] U1, first comparator; U2, second comparator; U3, second comparator; C1, capacitor; R1, first resistor; R2, second resistor; R3, third resistor; R4, fourth resistor; R5, fifth resistor; R6, sixth resistor; R7, seventh resistor; D1, diode; CT1, current transformer; U4, operational amplifier; U5, AND gate; U6, microcontroller; U7, drive chip. Detailed implementation manners

[0028] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments may be combined with each other. Now, with reference to the accompanying drawings, the preferred embodiments of the present invention will be described in detail.

[0029] An embodiment of the present invention provides an H-bridge drive protection circuit 200 for driving and protecting an H-bridge circuit 100. The voltage input terminal of the H-bridge circuit 100 is connected to an input power supply, the voltage output terminal is connected to the primary side of a transformer T1, and the secondary side of the transformer T1 is connected to a load terminal. Among them, with reference to Figure 2 , the H-bridge circuit 100 includes a first switching transistor Q1, a second switching transistor Q2, a third switching transistor Q3, and a fourth switching transistor Q4. The first switching transistor Q1 and the third switching transistor Q3 are connected in series, the second switching transistor Q2 and the fourth switching transistor Q4 are connected in series. The series connection node of the first switching transistor Q1 and the third switching transistor Q3 is connected to the same-named terminal of the primary side of the transformer T1, and the series connection node of the second switching transistor Q2 and the fourth switching transistor Q4 is connected to the different-named terminal of the primary side of the transformer T1. The drains of the first switching transistor Q1 and the second switching transistor Q2 are both connected to the input power supply, and the sources of the third switching transistor Q3 and the fourth switching transistor are both grounded. The input power supply may be a battery voltage or a bus voltage. Preferably, the input power supply of the H-bridge circuit 100 is a bus voltage, and the bus voltage supplies power to the H-bridge circuit 100.

[0030] As Figure 1 and Figure 2As shown, the H-bridge drive protection circuit 200 of the embodiment of the present application includes a drive module 210, a current anomaly detection module 220, a voltage anomaly detection module 230, and a signal processing module 240.

[0031] The drive module 210 is used to drive and control the working states of the switching tubes of the H-bridge circuit 100. The drive ends of the first switching tube Q1, the second switching tube Q2, the third switching tube Q3, and the fourth switching tube Q4 are all connected to the drive module 210. The drive module 210 outputs four SPWM signals to drive the first switching tube Q1, the second switching tube Q2, the third switching tube Q3, and the fourth switching tube Q4 respectively.

[0032] The current anomaly detection module 220 is used to detect the output current at the load end in real time and determine whether the output current is abnormal, and outputs a current judgment result.

[0033] The voltage anomaly detection module 230 is used to monitor the change of the input voltage of the H-bridge circuit 100 in real time and determine whether the input voltage is abnormal, and outputs a voltage judgment result.

[0034] The signal processing module 240 is connected to the current anomaly detection module 220 and the voltage anomaly detection module 230, and adjusts the working state of the drive module 210 based on the current judgment result and the voltage judgment result.

[0035] The H-bridge drive protection circuit 200 of the embodiment of the present application indirectly determines whether the switching tubes of the H-bridge circuit 100 are transmitting a large current by setting the current anomaly detection module 220 to detect the output current at the load end in real time and determine whether the output current is abnormal, and the voltage anomaly detection module 230 to monitor the change of the input voltage of the H-bridge circuit 100 in real time and determine whether the input voltage is abnormal, without directly collecting the input current of the H-bridge circuit 100. It has a wide current monitoring range, and cooperates with the abnormal situation of the output current at the load end detected by the current anomaly detection module 220 to control and adjust the working state of the drive module 210, and can drive and control the disconnection of the switching tubes of the H-bridge circuit 100 when an abnormal large current appears to achieve abnormal large current protection. Therefore, the present application can monitor a wide current range and perform abnormal large current protection without using devices with a large volume and a large weight, with low power loss and cost, and is beneficial to the miniaturization of the applied power equipment.

[0036] Reference Figure 1 and Figure 2, in an alternative embodiment of the present application, the voltage anomaly detection module 230 includes a first comparator U1 and a capacitor C1. The non-inverting input terminal of the first comparator U1 is connected to the voltage input terminal of the H-bridge circuit 100 and the first terminal of the capacitor C1, and the inverting input terminal is connected to the voltage input terminal of the H-bridge circuit 100. The output terminal of the first comparator U1 is connected to the first input terminal of the signal processing module 240, and the second terminal of the capacitor C1 is grounded. The capacitor C1 is used to store the input voltage of the H-bridge circuit 100 and use it as the voltage reference of the previous moment.

[0037] Under normal circumstances, the capacitor C1 stores the input voltage of the H-bridge circuit 100. The stored voltage is used as the voltage reference of the previous moment to provide a stable reference. That is, the first comparator U1 compares the current input voltage of the H-bridge circuit 100 with the input voltage of the previous moment. By comparing these two voltage values, the instantaneous change of the input voltage of the H-bridge circuit 100 is judged, so as to judge whether the input voltage of the H-bridge circuit 100 is abnormal. If there is a large fluctuation in the input voltage of the H-bridge circuit 100, such as an instantaneous drop exceeding 0.7V (usually caused by a large current passing through the switching tube of the H-bridge circuit 100), at this time, the voltage at the inverting input terminal of the first comparator U1 is lower than the voltage at the non-inverting input terminal, and the first comparator U1 outputs a high level, indicating that the input voltage of the H-bridge circuit 100 is abnormal, indicating that the input current of the H-bridge circuit 100 is abnormal. If the input voltage of the H-bridge circuit 100 is stable within the normal range, the voltage at the inverting input terminal of the first comparator U1 is higher than the voltage at the non-inverting input terminal, and the first comparator U1 outputs a low level, indicating that the input voltage of the H-bridge circuit 100 is normal, indicating that the input current of the H-bridge circuit 100 is normal. In this way, the voltage anomaly detection module 230 can accurately detect the instantaneous voltage drop caused by a large current, and can timely identify the abnormal situation of the switching tube of the H-bridge circuit 100 passing through a large current without directly collecting the input current of the H-bridge circuit 100, so as to ensure the safe operation of the H-bridge circuit 100 and the applied electrical equipment, improve the overall reliability and safety of the system, and moreover, the circuit structure is relatively simple.

[0038] Reference Figure 1 and Figure 2 , in an alternative embodiment of the present application, the voltage anomaly detection module 230 further includes a first resistor R1 and a second resistor R2. The first resistor R1 is connected in series between the voltage input terminal of the H-bridge circuit 100 and the first terminal of the capacitor C1, and the second resistor R2 is connected in series between the voltage input terminal of the H-bridge circuit 100 and the inverting input terminal of the first comparator U1.

[0039] The first resistor R1 limits the charging current of the capacitor C1, thereby extending the time for detecting the change in the input voltage of the H-bridge circuit 100 and avoiding the influence of instantaneous current changes on the detection result. The second resistor R2 limits the current input to the inverting input terminal of the first comparator U1, avoiding damage to the input pins of the first comparator U1. Therefore, setting the first resistor R1 and the second resistor R2 can improve the reliability of circuit detection. The resistance values of the first resistor R1 and the second resistor R2 can be set according to actual needs.

[0040] Further, the voltage anomaly detection module 230 further includes a diode D1 disposed between the voltage input terminal of the H-bridge circuit 100 and the first resistor R1. The positive electrode of the diode D1 is connected to the voltage input terminal of the H-bridge circuit 100, and the negative electrode is connected to one end of the first resistor R1.

[0041] The diode D1 is used to prevent the stored energy in the capacitor C1 from flowing back into the input voltage of the H-bridge circuit 100, thereby avoiding affecting the accuracy of the reference quantity and improving the reliability of the H-bridge drive protection circuit 200.

[0042] Reference Figure 1 and Figure 2 In an optional embodiment of the present application, the current anomaly detection module 220 includes a current sampling unit 221, a second comparator U2, a second comparator U2, and a third resistor R3. The current sampling unit 221 is used to collect the output current of the load end and convert it into a corresponding voltage signal. The inverting input terminal of the second comparator U2 and the non-inverting input terminal of the third comparator U3 are both connected to the output terminal of the current sampling unit 221. The non-inverting input terminal of the second comparator U2 is used to input a first reference voltage, and the inverting input terminal of the third comparator U3 is used to input a second reference voltage. The output terminals of the second comparator U2 and the third comparator U3 are both connected to the first end of the third resistor R3 and the second input terminal of the signal processing module 240, and the second end of the third resistor R3 is connected to an external power supply.

[0043] The current sampling unit 221 can collect the output current of the load end, transmit the output current to the second comparator U2 and the third comparator U3 for judgment, and obtain a current judgment result. Among them, since the output current of the load end is a sine wave current with a positive half-cycle and a negative half-cycle, by setting the second comparator U2 and the third comparator U3, the positive half-cycle and the negative half-cycle of the output current of the load end can be monitored respectively, effectively monitoring the abnormal situation of the output current of the load end, that is, judging whether the output current of the load end is too low.

[0044] Specifically, when it is detected that the positive half-cycle voltage of the output current at the load end exceeds the first reference voltage, the low level at the output end of the second comparator U2 indicates that the output current at the load end is normal; when it is detected that the negative half-cycle voltage of the output current at the load end is lower than the second reference voltage, the output end of the third comparator U3 outputs a low level, indicating that the output current at the load end is normal. Both belong to the situation where the output current at the load end is within the normal range. When the voltage signal corresponding to the output current at the load end is between the first reference voltage and the second reference voltage, both the output ends of the second comparator U2 and the third comparator U3 output a high level, indicating that the output current at the load end is abnormal, that is, the output current at the load end is too low.

[0045] Reference Figure 1 and Figure 2 In an alternative embodiment of the present application, the current sampling unit 221 includes a current transformer CT1, a fourth resistor R4, and an operational amplifier circuit. The two ends of the primary winding of the current transformer CT1 are respectively connected to the different-named ends of the secondary side of the transformer T1 and the load end, and the two ends of the secondary winding are respectively connected to the two ends of the fourth resistor R4 and the two input ends of the operational amplifier circuit. The fourth resistor R4 is connected in parallel between the two input ends of the operational amplifier circuit.

[0046] The current transformer CT1 can sense the large current in the connected circuit and convert it into a small current signal proportional to it. The conversion ratio is usually known, so the magnitude of the original current can be accurately reflected. And the current transformer CT1 can isolate the high-current loop (i.e., the load-end loop) from the measurement circuit, improving safety. Since the second comparator U2 and the third comparator U3 are used to detect whether the output current at the load end is too low, the current transformer CT1 used does not need to use a large-size and heavy-weight specification, with low power loss and low cost.

[0047] The small current signal converted by the current transformer CT1 is connected to the fourth resistor R4. When the current passes through the fourth resistor R4, according to Ohm's law, a voltage will be generated across the fourth resistor R4. This voltage signal is proportional to the original current and represents the current magnitude at present. This voltage signal is amplified by the operational amplifier circuit, and the amplitude of the signal is increased, thereby realizing the accurate sampling of the current. Through amplification, the signal is clearer and more convenient for subsequent processing and analysis. The amplified voltage signal is input to the second comparator U2 and the third comparator U3 for judgment to obtain the current judgment result.

[0048] Therefore, by setting the current transformer CT1, the fourth resistor R4, and the operational amplifier circuit to collect the output current at the load end, the large current can be accurately sampled and converted into a small voltage signal for subsequent system processing and analysis.

[0049] Further, reference Figure 2, the operational amplifier circuit includes an operational amplifier U4, a fifth resistor R5, a sixth resistor R6, and a seventh resistor R7. The fifth resistor R5 is connected in series between the first end of the fourth resistor R4 and the non-inverting input terminal of the operational amplifier U4. The sixth resistor R6 is connected in series between the second end of the first resistor R1 and the inverting input terminal of the operational amplifier U4. The seventh resistor R7 is connected in series between the output terminal and the inverting input terminal of the operational amplifier U4. The fourth resistor R4 is connected in parallel between the two input terminals of the operational amplifier U4.

[0050] By setting the fifth resistor R5, the sixth resistor R6, and the seventh resistor R7, combined with the operational amplifier U4, amplification processing of small voltage signals can be achieved, and a clearer voltage signal can be input into the second comparator U2 and the third comparator U3. The circuit structure is simple. Designers can obtain the required amplification factor by selecting different resistance value combinations, and the circuit application is flexible.

[0051] Reference Figure 1 And Figure 2 , in an alternative embodiment of the present application, the signal processing module 240 includes an AND gate U5. The first input terminal of the AND gate U5 is connected to the output terminal of the first comparator U1, the second input terminal is connected to the output terminals of the second comparator U2 and the third comparator U3, and the output terminal of the AND gate U5 is connected to the driving module 210.

[0052] By setting the AND gate U5, the current judgment result of the current anomaly detection module 220 and the voltage judgment result of the voltage anomaly detection module 230 are integrated, that is, the signals transmitted by the current anomaly detection module 220 and the voltage anomaly detection module 230 are received, and high and low levels are output to control the working state of the driving module 210. The circuit structure is simple. Among them, when either the second comparator U2 or the third comparator U3 outputs a low level, the voltage at the second input terminal of the AND gate U5 can be pulled low.

[0053] Specifically, when both input terminals of the AND gate U5 input high levels and the AND gate U5 outputs a high level, the enabling drive module 210 disconnects the output of the four-way SPWM signals (SPWM1, SPWM2, SPWM3, SPWM4), which causes the H-bridge circuit 100 to no longer receive drive signals, thereby stopping working, and the load cannot obtain power supply, achieving protection against abnormal conditions, ensuring that the device stops working in an abnormal state, and avoiding damage or faults. When there is no abnormality in the output current of the load terminal and the input voltage of the H-bridge circuit 100, or one of them is abnormal, and one of the two input terminals of the AND gate U5 inputs a low level and the AND gate U5 outputs a low level, the drive module 210 will conduct the four-way SPWM signals, restoring the drive control of the H-bridge circuit 100. At this time, the H-bridge circuit 100 starts to work, controls the normal operation of each switching tube of the H-bridge circuit 100, and further adjusts the current and voltage of the load. By comprehensively considering the output results of the first comparator U1, the second comparator U2, and the third comparator U3, that is, the input voltage of the H-bridge circuit 100 and the output current of the load terminal, the H-bridge circuit 100 can stop working when the input current is too large, ensuring the safe operation of the system and avoiding misjudgment at the same time. For example, when a very high-power load is connected to the load terminal, pulling down the input voltage of the H-bridge circuit 100, the input voltage is abnormal, which is a normal phenomenon, and the output current of the load terminal is normal, and it can work normally without the need to stop working.

[0054] In an alternative embodiment of the present application, the drive module 210 includes a single-chip microcomputer U6 and a drive chip U7. The single-chip microcomputer U6 is connected to the signal input terminal of the drive chip U7, and the enable terminal of the drive chip U7 is connected to the signal processing module 240.

[0055] By setting the single-chip microcomputer U6 and the drive chip U7, the single-chip microcomputer U6 can generate four-way SPWM signals according to the set frequency and phase. The four-way SPWM signals are then generated into SPWM1, SPWM2, SPWM3, and SPWM4 signals by the drive chip U7, respectively driving the first switching tube Q1, the second switching tube Q2, the third switching tube Q3, and the fourth switching tube Q4. Using the single-chip microcomputer U6 and the drive chip U7 to drive the working states of each switching tube of the H-bridge circuit 100, by setting an appropriate duty cycle through a program, precise control and adjustment functions are provided, the control is more flexible, and the single-chip microcomputer U6 integrates functions such as a processor, a memory, and input / output interfaces, which can be conveniently integrated with other peripheral components to achieve the integration of more functions. Its circuit integration degree is high, the overall circuit structure is simpler, the number of components on the circuit board can be reduced, thereby saving space, making the entire system more compact and efficient. It is beneficial to the miniaturization of the overall device.

[0056] Reference Figure 1 and Figure 2 , the H-bridge drive protection circuit 200 of the embodiment of the present application has multiple working states, specifically as follows:

[0057] (1) In the first working state:

[0058] Control and drive the H-bridge circuit 100 to normally conduct four SPWM signals (SPWM1, SPWM2, SPWM3, SPWM4), so that each switching tube of the H-bridge circuit 100 works normally.

[0059] ① Current and voltage monitoring:

[0060] The current anomaly detection module 220 monitors the output current in real time.

[0061] The voltage anomaly detection module 230 detects the input voltage of the H-bridge circuit 100 in real time.

[0062] ② Conditions:

[0063] When there is a load at the secondary output terminal of the transformer T1, and the output current at the load terminal is greater than the preset value, and at the same time the input voltage of the H-bridge circuit 100 is stable without large fluctuations, the voltage at the inverting input terminal of the first comparator U1 is higher than the voltage at the non-inverting input terminal. The first comparator U1 outputs a low level 0, pulling down the voltage at the first input terminal of the AND gate U5 of the signal processing module 240. The voltage at the inverting input terminal of the second comparator U2 is greater than the voltage at its own non-inverting input terminal. The second comparator U2 outputs a low level 0, or the voltage at the non-inverting input terminal of the third comparator U3 is lower than the voltage at the inverting input terminal. The third comparator U3 outputs a low level 0, which can all pull down the voltage at the second input terminal of the AND gate U5 of the signal processing module 240.

[0064] ③ Response of the signal processing module 240:

[0065] The signal processing module 240 receives the (0, 0) signal and outputs a low level 0. The drive module 210 receives the low level 0 and continues to normally conduct the four SPWM signals, and the H-bridge circuit 100 maintains normal operation.

[0066] (2) In the second working state:

[0067] Control and drive the H-bridge circuit 100 to normally conduct four SPWM signals (SPWM1, SPWM2, SPWM3, SPWM4), so that each switching tube of the H-bridge circuit 100 works normally.

[0068] ① Current and voltage monitoring:

[0069] The current anomaly detection module 220 monitors the output current in real time.

[0070] The voltage anomaly detection module 230 detects the input voltage of the H-bridge circuit 100 in real time.

[0071] ② Conditions:

[0072] When there is a load at the secondary output terminal of transformer T1, the output current at the load terminal is greater than the preset value, and the input voltage of H-bridge circuit 100 decreases compared to the voltage at the previous moment, the first comparator U1 outputs a high level 1, and the second comparator U2 and the third comparator U3 output a low level 0.

[0073] ③ Signal processing module 240 response:

[0074] The AND gate U5 of the signal processing module 240 receives the (0, 1) signal and outputs a low level 0. The drive module 210 receives the low level 0 and continues to normally conduct the four-way SPWM signals, and the H-bridge circuit 100 remains in normal operation.

[0075] (3) In the third working state:

[0076] Control and drive the H-bridge circuit 100 to normally conduct the four-way SPWM signals (SPWM1, SPWM2, SPWM3, SPWM4), so that each switching tube of the H-bridge circuit 100 operates normally.

[0077] ① Current and voltage monitoring:

[0078] The current anomaly detection module 220 monitors the output current in real time.

[0079] The voltage anomaly detection module 230 detects the input voltage of the H-bridge circuit 100 in real time.

[0080] ② Conditions:

[0081] When there is a load at the secondary output terminal of transformer T1, the output current at the load terminal is less than the preset value, and the input voltage of the H-bridge circuit 100 is stable without large fluctuations, the second comparator U2 and the third comparator U3 output a high level 1, and the first comparator U1 outputs a low level 0.

[0082] ③ Signal processing module 240 response:

[0083] The AND gate U5 of the signal processing module 240 receives the (1, 0) signal and outputs a low level 0. The drive module 210 receives the low level 0 and continues to normally conduct the four-way SPWM signals, and the H-bridge circuit 100 remains in normal operation.

[0084] (4) In the fourth working state:

[0085] Control and drive the H-bridge circuit 100 to normally conduct the four-way SPWM signals (SPWM1, SPWM2, SPWM3, SPWM4), so that each switching tube of the H-bridge circuit 100 operates normally.

[0086] ① Current and voltage monitoring:

[0087] The current anomaly detection module 220 monitors the output current in real time.

[0088] The voltage anomaly detection module 230 detects the input voltage of the H-bridge circuit 100 in real time.

[0089] ② Condition:

[0090] When there is a load at the secondary output terminal of the transformer T1, the output current at the load terminal is less than the preset value, and the input voltage of the H-bridge circuit 100 decreases compared to the previous moment, the first comparator U1, the second comparator U2, and the third comparator U3 all output a high level 1.

[0091] ③ Response of the signal processing module 240:

[0092] When the signal processing module 240 receives the (1, 1) signal, it outputs a high level 1. The drive module 210 receives the high level 1 and cuts off the four SPWM signals to achieve the drive protection of the H-bridge circuit 100 and stop the output of the H-bridge circuit 100.

[0093] In the first working state, the second working state, and the third working state, the output current at the load terminal and the input voltage of the H-bridge circuit 100 are not severely abnormal, and the H-bridge circuit 100 continues to work normally. In the fourth working state, both the output current at the load terminal and the input voltage of the H-bridge circuit 100 are abnormal, indicating that there is a short circuit or a large current in the H-bridge circuit 100. The drive signal of the H-bridge circuit 100 is controlled to be disconnected, and the H-bridge circuit 100 stops working, and the overall circuit enters the protection state.

[0094] Reference Figure 1 and Figure 2 Moreover, an embodiment of the present application further provides a power device, including the H-bridge circuit 100, the transformer T1, and the H-bridge drive protection circuit 200 as described above. The voltage input terminal of the H-bridge circuit 100 is connected to the input power supply, the voltage output terminal is connected to the primary side of the transformer T1, the secondary side of the transformer T1 is connected to the load terminal, the drive module 210 of the H-bridge drive protection circuit 200 is used to drive and control the working states of the switching tubes of the H-bridge circuit 100, the current anomaly detection module 220 is used to detect the output current at the load terminal and determine whether the output current is abnormal, and output the output current determination result. The voltage anomaly detection module 230 is used to monitor the input voltage of the H-bridge circuit 100 in real time and determine whether the input voltage is abnormal, and output the output voltage determination result.

[0095] In the power device of the embodiment of the present application, the H-bridge drive protection circuit 200 detects the output current at the load end in real time through the current anomaly detection module 220 and determines whether the output current is abnormal. The voltage anomaly detection module 230 monitors the change of the input voltage of the H-bridge circuit 100 in real time and determines whether the input voltage is abnormal, indirectly judging whether the switching tubes of the H-bridge circuit 100 are transmitting a large current, without directly collecting the input current of the H-bridge circuit 100, having a wide current monitoring range, and cooperating with the abnormal condition of the output current at the load end detected by the current anomaly detection module 220 to control and adjust the working state of the drive module 210, capable of driving and controlling to disconnect each switch of the H-bridge circuit 100 when the current is abnormal, realizing current anomaly protection. Therefore, the present application can realize the monitoring of a wide current range without using devices with a large volume and a large weight, with low power loss and cost, and is beneficial to the miniaturization of the applied power device.

[0096] The H-bridge drive protection circuit 200 in the power device has the same structure and technical effects as the aforementioned H-bridge drive protection circuit 200, and will not be elaborated here.

[0097] The power device can be a power frequency inverter, a high-frequency inverter, a switching power supply and other devices.

[0098] It should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. For those skilled in the art, the technical solutions recorded in the above embodiments can be modified, or some of the technical features can be equivalently replaced; and all such modifications and replacements should fall within the protection scope of the appended claims of the present invention.

Claims

1. An H-bridge driving protection circuit, used for driving protection of an H-bridge circuit, wherein the voltage input end of the H-bridge circuit is connected to an input power supply, the voltage output end is connected to the primary side of a transformer, and the secondary side of the transformer is connected to a load end, characterized in that: The H-bridge driving protection circuit comprises: A driving module, used to drive and control the working state of each switch tube of the H-bridge circuit; A current abnormality detection module, used to detect the output current of the load end in real time and determine whether the output current is abnormal, and output the current judgment result; A voltage anomaly detection module, used to monitor the change of the input voltage of the H-bridge circuit in real time and determine whether the input voltage is abnormal, and output a voltage determination result; A signal processing module is connected to the abnormal current detection module and the abnormal voltage detection module, and adjusts the working state of the driving module based on the current judgment result and the voltage judgment result.

2. The H-bridge driving protection circuit according to claim 1, characterized in that: The voltage anomaly detection module includes a first comparator and a capacitor, wherein the non-phase input terminal of the first comparator is connected to the voltage input terminal of the H-bridge circuit and the first end of the capacitor, and the reverse input terminal is connected to the voltage input terminal of the H-bridge circuit. The output terminal of the first comparator is connected to the first input terminal of the signal processing module, and the second end of the capacitor is grounded. The capacitor is used to store the input voltage of the H-bridge circuit and use it as the voltage reference at the previous moment.

3. The H-bridge driving protection circuit according to claim 2, characterized in that: The voltage anomaly detection module also includes a first resistor and a second resistor, the first resistor is connected in series between the voltage input end of the H-bridge circuit and the first end of the capacitor, and the second resistor is connected in series between the voltage input end of the H-bridge circuit and the inverting input end of the first comparator.

4. The H-bridge driving protection circuit according to claim 3, characterized in that: The voltage anomaly detection module further includes a diode disposed between the voltage input end of the H-bridge circuit and the first resistor, wherein the anode of the diode is connected to the voltage input end of the H-bridge circuit, and the cathode of the diode is connected to one end of the first resistor.

5. The H-bridge driving protection circuit according to claim 4, characterized in that: The current anomaly detection module includes a current sampling unit, a second comparator, a third comparator and a third resistor. The current sampling unit is used to collect the output current of the load end and convert it into a corresponding voltage signal. The inverting input end of the second comparator and the non-inverting input end of the third comparator are both connected to the output end of the current sampling unit. The non-inverting input end of the second comparator is used to input a first reference voltage, and the inverting input end of the third comparator is used to input a second reference voltage. The output ends of the second comparator and the third comparator are both connected to the first end of the third resistor and the second input end of the signal processing module, and the second end of the third resistor is connected to an external power supply.

6. The H-bridge driving protection circuit according to claim 5, characterized in that: The current sampling unit includes a current transformer, a fourth resistor and an operational amplifier circuit, wherein two ends of the primary winding of the current transformer are respectively connected to the opposite-name end of the secondary side of the transformer and the load end, and two ends of the secondary winding are respectively connected to two ends of the fourth resistor and two input ends of the operational amplifier circuit, and the fourth resistor is connected in parallel between the two input ends of the operational amplifier circuit.

7. The H-bridge driving protection circuit according to claim 6, characterized in that: The operational amplifier circuit includes an operational amplifier, a fifth resistor, a sixth resistor and a seventh resistor. The fifth resistor is connected in series between the first end of the fourth resistor and the non-inverting input terminal of the operational amplifier, the sixth resistor is connected in series between the second end of the first resistor and the inverting input terminal of the operational amplifier, the seventh resistor is connected in series between the output terminal and the inverting input terminal of the operational amplifier, and the fourth resistor is connected in parallel between the two input terminals of the operational amplifier.

8. The H-bridge driving protection circuit according to any one of claims 5 to 7, characterized in that: The signal processing module comprises an AND gate, a first input end of the AND gate is connected to the output end of the first comparator, a second input end is connected to the output end of the second comparator and the output end of the third comparator, and an output end of the AND gate is connected to the driving module.

9. The H-bridge driving protection circuit according to claim 1, characterized in that: The driving module comprises a single chip microcomputer and a driving chip. The single chip microcomputer is connected to a signal input terminal of the driving chip, and an enable terminal of the driving chip is connected to the signal processing module.

10. An electric power device, characterized in that: It comprises an H-bridge circuit, a transformer and an H-bridge driving protection circuit as described in any one of claims 1 to 9, wherein the voltage input end of the H-bridge circuit is connected to an input power supply, the voltage output end is connected to the primary side of the transformer, the secondary side of the transformer is connected to a load end, the driving module of the H-bridge driving protection circuit is used to drive and control the working state of each switch tube of the H-bridge circuit, the current anomaly detection module is used to detect the output current of the load end and determine whether the output current is abnormal, and output the current judgment result, and the voltage anomaly detection module is used to monitor the change of the input voltage of the H-bridge circuit in real time and determine whether the input voltage is abnormal, and output the voltage judgment result.

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