Trigger protection circuit for bridge circuit switching element

Abstract

The invention relates to a trigger protection circuit for a bridge circuit switch element, which only needs a single power supply to supply power, realizes screening and conditioning of an input end driving signal through a logic gate circuit combination, and realizes protection of the switch element through logic conversion. The risk caused by false triggering of the driving signal can be reduced, and direct connection is prevented; the trigger signal can be automatically recovered, the shutdown of the system after false triggering is avoided, the cost is low, the configuration is flexible, and the method is suitable for trigger control of a frequency converter, a digital automatic voltage regulator and other similar equipment on a switching device; by using the circuit provided by the invention, on the premise of ensuring the safety of components, the risk of system shutdown is reduced, and the circuit has a good application space.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic circuits, and particularly to a trigger protection circuit for a switching element of a bridge circuit. Background Art

[0002] Bridge circuits have been widely used in control systems such as AC inverters and DC motor controllers. With the gradual saturation of the electronic control market, drive manufacturers are facing competition challenges in terms of both cost and performance.

[0003] A bridge circuit is usually composed of two sets of switching devices connected in series. The upper and lower ends are powered by DC, and one end in the middle of the two sets of switching devices is used as the output. Since the switching tube conducts approximately as a short circuit when it is on, it is necessary to prevent the two sets of switching devices in the bridge circuit from conducting simultaneously, that is, to prevent shoot-through. In application scenarios with high reliability requirements, such as uninterruptible power supplies, generators, cranes, etc., the requirement of continuous operation during faults needs to be met. Therefore, the bridge trigger protection circuit needs to have a self-recovery function.

[0004] In the prior art, in order to prevent shoot-through faults in the two sets of switching devices in the bridge circuit, a chip with an enable function is usually used for protection. That is, when the trigger signals of the two sets of switching devices are both "1", the enable signal of the trigger is forced to "0", thereby cutting off the trigger signal to prevent shoot-through and protecting the two sets of switching devices in the bridge circuit. Although this can play a protective role, it is necessary to reset the enable protection of the chip again, and the enable protection reset time is usually much longer than the driving signal period, which greatly reduces the stability of the device and is also difficult to meet the application requirements for devices that cannot be shut down. Summary of the Invention

[0005] A trigger protection circuit for a switching element of a bridge circuit is proposed to solve the problems existing in the chip trigger of the bridge circuit. The protection and self-recovery functions of the bridge circuit can be realized only through "NOT gates" and "AND gates".

[0006] The technical solution of the present invention is: a trigger protection circuit for a switching element of a bridge circuit, including two inverters, two AND gates, and a power supply circuit for the inverters and AND gates;

[0007] The original drive signals 1A and 1B of two sets of switching devices on one arm are respectively subjected to logic conversion through two inverters to obtain inverted signals 1AR and 1BR;

[0008] The original drive signal 1A and the inverted signal 1BR are subjected to logic conversion through the first AND gate to obtain a new drive signal 1AD, and the original drive signal 1B and the inverted signal 1AR are subjected to logic conversion through the second AND gate to obtain a new drive signal 1BD;

[0009] The new driving signals 1AD and 1BD act on two groups of switching devices on one arm of a bridge as driving signals that satisfy anti-short-circuit and self-recovery requirements.

[0010] Preferably, the input signal of the trigger protection circuit is the original driving signals 1A and 1B of two groups of switching devices on one arm of a bridge, and the output signal is the driving signals of two groups of switching devices on one arm that satisfy anti-short-circuit and self-recovery requirements;

[0011] The signal conversion state of the trigger protection circuit is as follows:

[0012]

[0013] A trigger protection method for anti-short-circuit and self-recovery of bridge circuit switching elements forms driving signals that satisfy anti-short-circuit and self-recovery requirements by performing inverting logic and product logic conversions on the driving signals of two groups of switching devices on one arm of a bridge through two groups of logic circuits.

[0014] Furthermore, the inverting logic is to perform logic conversion on the initial driving signals through "NOT gates" respectively to obtain inverted signals; the product logic is to perform logic conversion on the initial driving signals and the inverted signals through "AND gates" respectively to obtain new driving signals, realizing anti-short-circuit and uninterrupted self-recovery during the conversion of driving signals.

[0015] The beneficial effects of the present invention are as follows: The trigger protection circuit of the present invention for bridge circuit switching elements only needs to be powered by a single power supply. Through the combination of logic gate circuits, the screening and conditioning of the input driving signals are realized, and the protection of the switching devices is realized through logic conversion; it can not only reduce the risk caused by mis-triggering of the driving signals and prevent short-circuit, but also automatically restore the trigger signal to avoid the shutdown of the system after mis-triggering. It has low cost, flexible configuration, and is suitable for the trigger control of switching devices in similar equipment such as frequency converters and digital automatic voltage regulators; using the circuit provided by the present invention, the risk of system shutdown is reduced on the premise of ensuring the safety of components, and it has good application prospects. Description of the Drawings

[0016] Figure 1 It is a schematic diagram of a conventional bridge circuit;

[0017] Figure 2 It is the trigger protection circuit diagram of the present invention for bridge circuit switching elements. Detailed Embodiments

[0018] The present invention will be described in detail below with reference to the drawings and specific embodiments. This embodiment is implemented on the premise of the technical solution of the present invention, and the detailed implementation manners and specific operation processes are given, but the protection scope of the present invention is not limited to the following embodiments.

[0019] AsFigure 1 The figure shows a schematic diagram of a conventional bridge circuit. The series-connected VT1 and VT2 are two sets of switching devices on one arm of the bridge. The original drive signal of VT1 is set to 1A, and the original drive signal of VT2 is set to 1B.

[0020] As Figure 2 The figure shows a trigger protection circuit diagram for the switching elements of a bridge circuit. The circuit includes "NOT gates", "AND gates" and the surrounding circuits. Through two sets of logic circuits, the drive signals of two sets of switching devices on one arm of the bridge are subjected to inversion logic and product logic conversions to form drive signals that meet the anti-short-circuit and self-recovery requirements. The inversion logic is to respectively perform logic conversion on the initial drive signals "1A" and "1B" through "NOT gates" to obtain inverted signals "1AR" and "1BR". The product logic is to respectively perform logic conversion on the initial drive signals "1A" and "1B" and the inverted signals "1AR" and "1BR" through "AND gates" to obtain new drive signals "1AD" and "1BD". The surrounding circuits are power supply circuits that ensure the normal operation of the inverters and AND gates.

[0021] The original drive signals 1A and 1B are respectively passed through "NOT gates" U11 and U12 to obtain signals 1AR and 1BR; then 1A and 1BR pass through "AND gate" U21 to form a new drive signal 1AD, and 1B and 1AR pass through "AND gate" U22 to form a new drive signal 1BD.

[0022] When the drive signals 1A and 1B on both switching devices VT1 and VT2 are both "1", it means that both switching devices on this arm of the bridge will be turned on. Through Figure 2 the trigger protection circuit, they are first respectively converted into signals "0" through inverters. The "0" and "1" input to the AND gate are subjected to AND gate logic conversion, and the new drive signals 1AD and 1BD will all be converted into signals "0", thus preventing the problem of short-circuit of this arm of the bridge.

[0023] When the drive signals 1A and 1B on both switching devices VT1 and VT2 are restored to the combination of "0" and "1", through Figure 2 the trigger protection circuit, they are first respectively converted into signals 1AR "1" and 1BR "0" through inverters. 1A "0", 1BR "0" are subjected to AND gate logic conversion to make 1AD "0", 1B "1", 1AR "1" are subjected to AND gate logic conversion to make 1BD "1". The new drive signals 1AD and 1BD can still maintain the signal states of 1A and 1B for transmission, thus playing a self-recovery function.

[0024] The signal conversion states of the protection circuit of the present invention are as follows:

[0025]

[0026] The embodiments described above only represent specific implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all fall within the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A trigger protection circuit for a bridge circuit switch element, characterized in that: It includes two inverters, two AND gates and power supply circuits of the inverters and the AND gates; The original drive signals 1A and 1B of the two groups of switch devices on one bridge arm are respectively converted by two inverters to obtain inverted signals 1AR and 1BR. The original driving signal 1A and the negated signal 1BR are logically converted through the first AND gate to obtain a new driving signal 1AD, and the original driving signal 1B and the negated signal 1AR are logically converted through the second AND gate to obtain a new driving signal 1BD; The new drive signals 1AD and 1BD act on two groups of switch devices on one bridge arm as drive signals that meet the requirements of anti-shoot-through and self-recovery.

2. The trigger protection circuit for a bridge circuit switch element according to claim 1, characterized in that: The input signal of the trigger protection circuit is the original drive signal 1A and 1B of two groups of switch devices on one bridge arm, and the output signal is the drive signal of two groups of switch devices on one bridge arm that meets the requirements of anti-through and self-recovery; the signal conversion state of the trigger protection circuit is as follows:

3. A trigger protection method for preventing direct conduction and self-recovery of a bridge circuit switch element, characterized in that: The drive signals of two groups of switch devices on one bridge arm are converted into inversion logic and product logic through two groups of logic circuits to form a drive signal that meets the requirements of anti-shoot-through and self-recovery.

4. The trigger protection method for preventing direct conduction and self-recovery of a bridge circuit switch element according to claim 3, characterized in that: The inversion logic is to perform logic conversion on the initial driving signal through the "NOT gate" to obtain the inverted signal; the product logic is to cross the initial driving signal and the inverted signal and perform logic conversion through the "AND gate" to obtain a new driving signal, thereby realizing anti-straight-through and uninterrupted self-recovery during the driving signal conversion.

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