An inverter power supply overcurrent protection circuit

Abstract

The present invention relates to an inverter power supply protection circuit. An inverter power supply overcurrent protection circuit includes a detection sampling circuit and a comparison processing circuit, and is characterized in that: the detection sampling circuit is respectively connected to the source terminals of two output switch tubes, and the two drive pulse outputs of the drive circuit are respectively connected to the two push-pull amplifiers through current limiting resistors and embedded diodes, and the output ends of the two push-pull amplifiers are respectively connected to the control electrodes of the output switch tubes through current limiting resistors, and the base of the comparison circuit comparator is connected to the voltage regulator tube of the sampling circuit through an embedded resistor, and the collector of the comparator is connected to the connection node of the embedded diodes of the two push-pull amplifiers, and the node is connected to the working power supply through a pull-up resistor. The inverter power supply overcurrent protection circuit of the present invention has a unique protection method, fast and reliable protection and recovery, is easy to use, and has stable and reliable performance.

Description

Technical Field

[0001] The invention relates to an inverter power supply protection circuit, in particular to an inverter power supply overcurrent / short circuit protection circuit. Background Art

[0002] Inverter power supply is widely used in various industries and fields because of its convenience and portability. However, it is precisely because the use environment of inverter power supply is mostly in a place with complex external environment that its stability and safety directly determine its performance and convenience of use. Moreover, due to the different working environment and the user object, the fault impact on the equipment itself during use is also very uncertain. Regardless of various power tools and equipment, there will be more or less overcurrent / short circuit faults during use, which will cause equipment damage in serious cases. Therefore, it is necessary to test the safety performance of the equipment during operation and use and adopt overcurrent and short circuit protection. The current overcurrent and short circuit protection circuit usually detects the size of the loop current value. When the set value is reached, the overcurrent point is reached, the protection circuit is activated, and the short circuit is regarded as the limit state of overcurrent. Under normal circumstances, when the inductive and capacitive loads are started or stopped, the instantaneous value of the current will exceed the current limit point, and the protection circuit cannot be frequently activated, so the execution circuit must have a delay, and the damage of the device is in an instant. Therefore, the development of complete equipment safety protection measures is a prerequisite for the normal and safe use of equipment. The key to inverter power supply overcurrent protection lies mainly in the protection of the power tube.

[0003] Existing overcurrent and short-circuit protection solutions have complex structures, slow operation, and poor protection reliability. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention proposes an inverter power supply overcurrent protection circuit, which has unique short circuit and overcurrent protection modes, fast and reliable protection and recovery, is easy to use, and has stable and reliable performance.

[0005] Technical solution adopted by the invention:

[0006] An inverter power supply overcurrent protection circuit includes a detection sampling circuit and a comparison processing circuit. The detection sampling circuit is respectively connected to the source terminals U3VS and U4VS of two output switch tubes. The two drive pulse outputs of the drive circuit are respectively connected to two push-pull amplifiers through current limiting resistors and embedded diodes. The output terminals U3LO and U4LO of the two push-pull amplifiers are respectively connected to the control electrodes of the output switch tubes through current limiting resistors. The base of the comparison circuit comparator Q10 is connected to the voltage regulator tube D19 of the sampling circuit through the embedded resistor. The collector of the comparator is connected to the connection node of the embedded diodes of the two push-pull amplifiers, and the node is connected to the working power supply through a pull-up resistor.

[0007] The inverter power supply overcurrent protection circuit, the sampling circuit is composed of a switch diode D13, a resistor R54, a diode D17 connected to the output switch tube I, and a switch diode D9, a resistor R53, and a diode D15 connected to the output switch tube II, and connected to the voltage regulator tube D19, and then grounded through a filter capacitor. The negative terminal of the voltage regulator tube D19 is connected to the base of the comparison circuit comparator Q10 through a resistor R59; the driving pulse is connected to the connection node of the resistor R5 and the diode D17 in the sampling circuit through a resistor R56, and is connected to the connection node of the resistor R54 and the diode D15 in the sampling circuit through a resistor R57. A grounding resistor is connected between the pulse input end of the driving circuit and the ground.

[0008] In the inverter power supply overcurrent protection circuit, the collector output of the comparator Q10 of the comparison circuit is connected to two isolation diodes D18 and D16 and a photoelectric coupler, and the output SD end of the photoelectric coupler is connected to the control circuit.

[0009] In the inverter power supply overcurrent protection circuit, two driving pulse signals are connected to the output switch tube through push-pull output amplifiers (composed of transistors Q8, Q9 and Q6, Q7 respectively); the bases of the two push-pull output amplifiers are connected to the collector output end of the comparator Q10 through isolation diodes D16, D18 respectively.

[0010] Beneficial effects of the invention:

[0011] 1. The inverter power supply overcurrent protection circuit of the present invention combines current detection with the determination of the current rise and fall rate. When the current continues to increase and exceeds the current limit, it delays protection within the tolerance range of the device and shuts off the output. When a short circuit or strong impact occurs, the current increases instantaneously, and di / dt exceeds the set limit. The protection circuit acts synchronously to reduce the drive and reduce power consumption to achieve the protection effect. The circuit design is reasonable, the structure is simple, the cost is low, and it has good promotion and application value.

[0012] 2. The inverter power supply overcurrent protection circuit and short circuit protection of the present invention adopt a unique circuit structure, bus current and IGBT tube voltage drop detection composite control, to ensure high reliability and stability. The protection function unit always monitors the working status of the whole machine. Once an abnormality occurs, it will act quickly and shut down the output to ensure that the machine and electrical equipment are not damaged. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a schematic diagram of an inverter power supply overcurrent protection circuit of the present invention;

[0014] Figure 2 The present invention is a block diagram of the practical application principle of the inverter power supply overcurrent protection circuit. DETAILED DESCRIPTION

[0015] The technical solution of the present invention is further described in detail below through specific implementation modes and in conjunction with the accompanying drawings.

[0016] Example 1

[0017] See also Figure 1 The inverter power supply overcurrent protection circuit of the present invention includes a detection sampling circuit and a comparison processing circuit. The detection sampling circuit is respectively connected to the source terminals U3VS and U4VS of two output switch tubes (the output switch tubes are not shown in the figure). The two driving pulse outputs of the driving circuit are respectively connected to the two push-pull amplifiers through current limiting resistors and embedded diodes. The output terminals U3LO and U4LO of the two push-pull amplifiers are respectively connected to the control electrodes of the output switch tubes through current limiting resistors. The base of the comparator Q10 of the comparison circuit is connected to the voltage regulator tube D19 of the sampling circuit through an embedded resistor. The collector of the comparator is connected to the connection node of the embedded diodes of the two push-pull amplifiers, and the node is connected to the working power supply through a pull-up resistor.

[0018] The inverter power supply overcurrent protection circuit of the present invention realizes the overcurrent self-protection of the inverter power supply, and effectively protects the output switch tube (power tube) from being burned and damaged due to overcurrent (even if it does not pass through the control circuit). The protection function unit monitors the working status of the whole machine at all times. Once an abnormality occurs, it will act quickly to shut down the output, thereby protecting the machine and electrical equipment from damage.

[0019] Example 2

[0020] See also Figure 1 The inverter power overcurrent protection circuit of this embodiment is different from that of Embodiment 1 in that: further, the sampling circuit is composed of a switching diode D13, a resistor R54, and a diode D17 connected to the output switch tube I, and a switching diode D9, a resistor R53, and a diode D15 connected to the output switch tube II, and is connected to a voltage-stabilizing diode D19, and then grounded through a filter capacitor, and the negative terminal of the voltage-stabilizing tube D19 is connected to the base of the comparator Q10 of the comparison circuit through a resistor R59; the driving pulse is connected to the connection node of the resistor R54 and the diode D17 in the sampling circuit through a resistor R56, and is connected to the connection node of the resistor R53 and the diode D15 in the sampling circuit through a resistor R55.

[0021] Overcurrent protection action process:

[0022] When the equipment is working normally, during the high level period of the driving pulse, the push-pull amplifier circuit (Q6, Q7, Q8, Q9) works through the current limiting resistor R58 or R57, the output switch tube is turned on, and the output current is within the allowable range. At this time, u3vs and u4vs are at a low level, D13 and D9 are turned on, D17 and D15 are turned off, D19 is blocked, Q10 is cut off, and the protection circuit does not operate; during the low level period of the driving pulse, the positive levels of D15 and D17 are pulled down through R55 and R56 respectively, D19 is blocked, Q10 is cut off, and the protection circuit does not operate.

[0023] When an overcurrent (short circuit) condition occurs, the output current increases, and the voltage drop of the output switch tube I (power tube) increases, then the voltage at the detection point U3Vs rises, turning off the switch diode D13, and the high level of the driving pulse passes through the resistor R56, turning on the diode D17, and the voltage reaches the voltage limit value of the voltage regulator tube D19, causing D19 to break down and turn on. Through the resistor R59, the high level is added to the base of the transistor Q10, turning on Q10, and the collector drops to a low level, turning on the diode D18, and the base of the push-pull transistors Q8 and Q9 drops to a low level, and the output terminal U3Lo is low, turning off the output, which plays a role in protecting the output tube. When the overcurrent or short circuit condition disappears, the U3VS state is restored and the equipment works normally.

[0024] For output switch tube II, the working process is the same as above.

[0025] Example 3

[0026] See also Figure 1 , Figure 2 The inverter power overcurrent protection circuit of this embodiment is different from that of Embodiment 2 in that, further, the collector output of the comparator Q10 of the comparison circuit is connected to two isolation diodes D18, D16 and a photocoupler, and the output SD end of the photocoupler is connected to a drive pulse generating circuit.

[0027] When an overcurrent (short circuit, overload) condition occurs, the control signal turns off the push-pull output through diodes D16 and D18, and at the same time, outputs a signal SD through the optocoupler U6 to stop the front-stage drive pulse generating circuit from working.

[0028] Example 4

[0029] See also Figure 1 , Figure 2 The inverter power supply overcurrent protection circuit of this embodiment is different from that of embodiment 2 in that, further,

[0030] The two drive pulse signals are connected to the output switch tube through push-pull output amplifiers (two push-pull output amplifier circuits composed of transistors Q8, Q9 and Q6, Q7 respectively); the bases of the two push-pull output amplifiers are connected to the collector output terminal of the comparator Q10 through isolation diodes D16, D18 respectively.

[0031] The inverter power supply overcurrent protection circuit of the present invention has a surge protection diode connected in parallel at both ends of a current limiting resistor connecting a driving circuit and a push-pull amplifier, and a grounding resistor connected between a pulse input end of the driving circuit and the ground.

[0032] The inverter power supply overcurrent protection circuit of the present invention combines current detection with the determination of the current rise and fall rate. When the current continues to increase and exceeds the current limit point, it delays protection within the tolerance range of the device and shuts off the output. When a short circuit (overcurrent, overload) or a strong impact occurs, the current increases instantaneously, and the di / dt exceeds the set limit. The protection circuit acts synchronously to reduce the drive and reduce the power consumption to achieve the protection effect.

[0033] The above embodiments are only used to illustrate the present invention and should not be construed as limiting the scope of protection of the patent claims of the present invention. Those skilled in the art can make other modifications to the implementation of the present invention or replace it with conventional technical means in the art in combination with the prior art without creative work, and as long as they do not deviate from the spirit and scope of the technical solution of the present invention, they should be included in the scope of the claims of the present invention.

Claims

1. An inverter power supply overcurrent protection circuit, comprising a detection sampling circuit and a comparison processing circuit, characterized in that: The detection sampling circuit is connected to the source terminals (U3VS, U4VS) of the two output switch tubes respectively, the two driving pulse signals of the driving circuit are connected to the two push-pull amplifiers through the current limiting resistors and the embedded diodes respectively, the output terminals (U3LO, U4LO) of the two push-pull amplifiers are connected to the control electrodes of the output switch tubes through the current limiting resistors respectively, the bases of the two push-pull output amplifiers are connected to the collector output terminal of the comparator Q10 in the comparison processing circuit through the isolation diodes D16, D18, the embedded diodes respectively; the base of the comparator Q10 is connected to the voltage regulator tube D19 of the detection sampling circuit through the embedded resistor, the collector of the comparator is connected to the connection node of the embedded diodes of the two push-pull amplifiers, and the node is also connected to the photocoupler The output SD end of the photoelectric coupler is connected to the control circuit, and its input end is connected to the working power supply through a pull-up resistor; the sampling circuit is composed of a switching diode D13, a resistor R54, and a diode D17 connected to the output switch tube I, and a switching diode D9, a resistor R53, and a diode D15 connected to the output switch tube II, and is connected to the voltage regulator tube D19, and then grounded through a filter capacitor. The negative terminal of the voltage regulator tube D19 is connected to the base of the comparator Q10 in the comparison processing circuit through a resistor R59; the driving pulse signal is connected to the connection node of the resistor R5 and the diode D17 in the sampling circuit through a resistor R56, and is connected to the connection node of the resistor R54 and the diode D15 in the sampling circuit through a resistor R57.

2. The inverter power supply overcurrent protection circuit according to claim 1 is characterized in that: A grounding resistor is connected between the pulse signal input terminal of the driving circuit and the ground.

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