阅读说明：本技术 一种mos管分流关断的可控硅开关电路 (Silicon controlled switch circuit switched off by shunting of MOS (metal oxide semiconductor) tube ) 是由 何志毅 卯龙 犹元彬 陈礼傲 郑岩 于 2021-09-24 设计创作，主要内容包括：本发明提供了一种MOS管分流关断的可控硅开关电路,可控硅具有高反向耐压和大峰值电流承受能力,适用于对容性负载如电致发光器件的控制。可控硅在触发导通后即使撤除门极控制电压/电流,在一定工作电流以上(维持电流)会一直处于自锁导通状态而不会自行关断。在本发明容性负载驱动电源半桥开关电路中,可控硅导通时承担容性负载充放电的瞬时峰值大电流,在其两端并联MOS管并分担开关电路导通后的持续电流,对所述可控硅短接分流使它工作在维持电流以下从而在其门极无电流输入时能够关断,使所述开关电路能够正常工作并保证高峰值电流冲击下的可靠性。(The invention provides a silicon controlled rectifier switching circuit with a MOS tube shunt cut-off function, wherein a silicon controlled rectifier has high reverse withstand voltage and large peak current bearing capacity and is suitable for controlling capacitive loads such as an electroluminescent device. Even if the gate control voltage/current is removed after the silicon controlled rectifier is triggered and switched on, the silicon controlled rectifier is always in a self-locking on state and cannot be automatically switched off when a certain working current (maintaining current) is exceeded. In the capacitive load driving power supply half-bridge switching circuit, the thyristor bears instantaneous peak value heavy current charged and discharged by a capacitive load when being conducted, the MOS tube is connected in parallel at two ends of the thyristor and shares continuous current after the switching circuit is conducted, the thyristor is in short circuit and shunted to work below holding current so as to be turned off when no current is input at a gate pole of the thyristor, so that the switching circuit can normally work and the reliability under high peak value current impact is ensured.)

1. The utility model provides a silicon controlled rectifier switch circuit that MOS pipe reposition of redundant personnel was shut off, includes silicon controlled rectifier and MOS pipe, characterized by: MOS tubes are connected in parallel at the two ends of the anode and the cathode of the controlled silicon, the controlled silicon is used as a switching device to bear the high peak current of capacitive load when the switching circuit is switched on, and the MOS tubes are connected in parallel to delay the short circuit and the turn-off of the controlled silicon by the switch; two paths of pulse signals are input into two control units of the switch circuit, wherein one path of pulse is delayed from the other path of pulse, and the two paths of pulse signals respectively control the switch of the silicon controlled rectifier and the delay switch of the parallel MOS tube.

2. The thyristor switching circuit of claim 1, wherein: the control unit consists of a switch circuit control chip; the control unit controls switching of the switching transistor by a pulse input signal and a pulse output signal, wherein:

the pulse input signal is divided into two paths, wherein one path is delayed by an RC circuit and then input to a pulse shaping circuit for shaping to generate delay pulse, and the switch of the silicon controlled rectifier parallel MOS tube is controlled to realize the purposes of short circuit and shunt of the silicon controlled rectifier;

the pulse output signal controls the MOS tube connected with the controlled silicon in parallel by the delay pulse after the delay and shaping of the RC circuit, so that the MOS tube is switched on and off in a delay way, and the controlled silicon is shunted and switched off.

3. The thyristor switching circuit of claim 1, wherein: the capacitive load is an electroluminescent screen.

4. The thyristor switching circuit of claim 1, wherein: the pulse shaping circuit is a totem-pole structure or an MOS tube driving chip, and the working voltage of the pulse shaping circuit is provided after the pulse shaping circuit outputs pulses and is rectified by a switch circuit control chip of the control unit.

Technical Field

The invention relates to the field of electroluminescent devices and switching power supplies, in particular to a silicon controlled switch circuit for driving shunt shutoff by using an MOS (metal oxide semiconductor) tube, which is used for driving the electroluminescent devices.

Background

The electroluminescent device is a flexible and bendable light and thin surface light source or a line light source, is mostly applied to the fields of decoration, illumination and advertisement, and has the structure that a luminescent powder thin layer is clamped between electrode layers at two sides, wherein the light emitting side is a transparent electrode, similar to a flat capacitor, electrons in the luminescent layer are accelerated under the action of electric fields applied by the electrode layers at two sides and then collide with a luminescent center to emit visible light, and the load characteristic of the electroluminescent device is represented as capacity.

In the high-voltage alternating current driving process of an electroluminescent device, peak heavy current at the moment of charge/discharge can reach more than dozens to one hundred amperes due to the capacitive load characteristic of the electroluminescent device, an MOS (metal oxide semiconductor) tube is adopted as a switching device in a general switching circuit, the MOS tube is a transistor with a conductive channel, the channel is easily burnt by the density of the instantaneous heavy current, and particularly when the working temperature of the transistor is higher. Therefore, the reliability of the switch circuit is difficult to ensure, and the requirement of heat dissipation conditions is high. A Bipolar Junction Transistor (BJT) has a small input impedance and is not easily controlled in a switching circuit; the IGBT transistor combines the advantages of high input impedance of an MOS transistor and conduction of a BJT body, but the performance and cost performance of the IGBT transistor for bearing peak large current are still not as good as those of a thyristor (silicon controlled rectifier), but the silicon controlled rectifier can be self-locked and can not be automatically turned off after being triggered and conducted, and the IGBT transistor can not be independently used as a switching device. Although there are turn-off thyristors (GTOs), they are large in size and inconvenient for the compact design of the driving power supply; in addition, a thyristor and a composite switching device (MCT) of a MOS transistor also have the same problems as the GTO.

Therefore, chinese patent CN111130311A discloses a delay turn-on circuit of an electroluminescence screen driving switching power supply, which utilizes a delay turn-on circuit designed at the output end of a switching circuit by a unidirectional thyristor with large capacity for bearing peak current, and the output end delays to turn on a capacitive load after an MOS transistor in a half-bridge switching circuit is turned on, so that the large current for charging and discharging the capacitive load passes through the switching circuit in a low-resistance state after the MOS transistor is completely turned on, thereby reducing the switching loss of the MOS transistor, which is actually equivalent to the switching loss of the high peak current of the MOS transistor, and is transferred to the thyristor with larger allowable peak current. However, the delay conduction time of the delay circuit is unstable and needs to be debugged, and meanwhile, power loss is generated on the silicon-controlled rectifier, so that the overall electric power efficiency is reduced. But still needs to solve the problem that the thyristor can not be turned off by itself.

Disclosure of Invention

In order to solve the technical problem, the invention provides a silicon controlled switch circuit using MOS tube shunt cut-off, which uses a one-way silicon controlled as a switch device, the MOS tube is connected in parallel at two ends of the one-way silicon controlled and is delayed to be switched on/off, the silicon controlled bears the instantaneous peak value heavy current when the switch circuit is switched on, and the MOS tube bears the continuous current after the switch circuit is switched on, so as to ensure the reliability of the switch circuit driving the electroluminescent device to work with high peak value current in capacitive load.

The technical scheme for realizing the aim of the invention is as follows:

the utility model provides an utilize silicon controlled rectifier switching circuit that MOS pipe reposition of redundant personnel was shut off, includes silicon controlled rectifier and MOS pipe, is different with prior art: two MOS tubes are respectively connected in parallel at the two ends of the anode and the cathode of the controllable silicon of two switching devices of the half-bridge circuit, the controllable silicon bears the high peak current of capacitive load when the switching circuit is switched on, the MOS tubes are controlled by two paths of reverse pulse signals of the switching power supply control unit, two paths of pulse signals are respectively input into the two switching circuit control units, one path of pulse is delayed than the other path of pulse, and the switch of the controllable silicon and the delay switch of the parallel MOS tubes are respectively controlled.

The control unit consists of a switch circuit control chip; the pulse output of the control unit is synchronously controlled by a pulse input signal, and then the switch of the transistor is controlled by a pulse output signal, wherein:

the pulse input signal is divided into two paths, wherein one path is input into the switch circuit control unit to generate delay pulse after being shaped by the RC circuit delay and shaping circuit, and the switch of the silicon controlled rectifier parallel MOS tube is controlled, so that the aims of short-circuit and shunt of the silicon controlled rectifier are fulfilled;

the above method needs two switch circuit control units, and the structure is complicated. Another MOS transistor delay control scheme may be that a single switch circuit control unit directly controls the thyristor by a pulse output signal, and then the pulse output signal is connected to another MOS transistor in parallel controlled by a delay pulse delayed and shaped by an RC circuit, so that the MOS transistor is delayed to be turned on and off, and the thyristor is shunted and turned off.

The capacitive load is an electroluminescent screen.

The pulse shaping circuit is a totem-pole structure or an MOS tube driving chip, and the working voltage of the pulse shaping circuit is provided after the pulse shaping circuit outputs pulses and is rectified by a switch circuit control chip of the control unit.

The invention has the beneficial effects that: aiming at the capacitive load characteristics of the electroluminescent device, the drive power supply which is designed with the silicon controlled switch circuit and is switched off by shunting through the parallel MOS tube is also suitable for driving other capacitive loads, in particular but not only suitable for driving capacitive loads such as the electroluminescent device and the like.

Drawings

Fig. 1 is a schematic diagram of a thyristor half-bridge switching circuit with parallel MOS transistors for delaying on-off, two common-ground signals of SCR1 and SCR2 are converted into two non-common-ground signals through IR2110 pulse synchronous conversion, and the two non-common-ground signals are output from high and low ends of HO and LO to control two thyristor switches. The drain electrode and the source electrode of the MOS tube are respectively connected to the two ends of the anode and the cathode of the controlled silicon in parallel.

Fig. 2 is a waveform diagram of control pulses of the thyristors and the MOS transistors, the SCR1 and the SCR2 are control pulses with a certain frequency and duty ratio, the MOS1 and the MOS2 are pulses obtained by delaying the SCR1 and the SCR2 by an RC circuit for about 0.1% of a period, and shaping the pulses, and the control pulses of the two MOS transistors lag behind the respective parallel thyristors. The trigger pulses of the controllable silicon and the MOS tube are in a complementary state, and a dead time period exists when the drive pulses are all low level.

Fig. 3 is a schematic diagram of an input pulse generating circuit of a half-bridge circuit control unit, which generates two pulses HIN and LIN by using a PWM pulse generating circuit or a PWM chip (for example, SG 3525).

Fig. 4 is another output pulse delay control circuit diagram of the MOS transistor shunt turn-off thyristor switch circuit, which delays the output pulse of the control unit and controls two MOS transistors after being shaped by the totem pole circuit. The totem-pole circuit is mainly used for accelerating the rising edge and the falling edge of the pulse so as to reduce the switching loss of the controlled MOS tube.

Detailed Description

The invention is further illustrated with reference to the following figures and examples.

The switching power supply circuit realizes the functions of controlling output voltage/current or power and the like by frequency conversion and Pulse Width Modulation (PWM) through two working states of on (conducting) and off (stopping) of the transistor. The invention adds a half-bridge circuit of an MOS tube shunt turn-off silicon controlled rectifier, so that the instantaneous peak current in the switch circuit is born by the silicon controlled rectifier, the MOS tube is connected in parallel at two ends of the silicon controlled rectifier, after the silicon controlled rectifier is in a short circuit state after being in delayed conduction, the control of the silicon controlled rectifier is realized when the silicon controlled rectifier is turned off, the continuous current of a certain time after the peak current is passed is shared, the conduction time of the MOS tube is controlled, the loss and the working temperature of the MOS tube and the silicon controlled rectifier are the same or similar, the relative balance is achieved, and the reliability of the drive circuit is further ensured.

Taking a half-bridge circuit commonly used for an alternating current output switching power supply as an example, generally, MOS transistors with high input impedance are adopted for convenient control, and two MOS transistors are connected in series to two ends of a direct current power supply and are alternately switched on and off under the control of two external opposite-phase pulses to form alternating current output. The MOS transistors connected to the positive supply and to ground are referred to as high-side and low-side transistors, respectively. The invention takes two thyristors as switching devices to bear high peak current for driving capacitive load, and as shown in fig. 1 (a) and (b), the invention is respectively a half-bridge switching circuit with thyristors connected in parallel with MOS tubes and a circuit schematic diagram of a control unit thereof. The thyristor can not be automatically turned off after being triggered and turned on, the two ends of the thyristor are respectively connected with an MOS tube in parallel, and the MOS tubes are in shunt short connection with the two ends of the anode and the cathode of the thyristor after being delayed and turned on, so that the thyristor is also turned off when the MOS tubes are delayed and turned off. According to the timing chart of the drive pulse of the two thyristors and the two MOS transistors shown in fig. 2, the conduction and cut-off delay time of the MOS transistors is properly controlled to make the thyristors reliably turned on and off in a working period to ensure the safe operation of the switching circuit, and each MOS transistor is turned on under the control of the external control circuit after the conduction peak current of the thyristor controlled by the MOS transistor passes through, and is cut off before the current half period of the switching circuit is finished, that is, before the other thyristor in the next half period is turned on. The MOS tube can bear continuous current after the peak current passes, so that the power loss of the controllable silicon is reduced.

Because the high-side and low-side transistors of the half-bridge circuit are not connected in common, a special chip (such as IR 2110) controlled by the half-bridge circuit can convert two paths of common-ground reverse-phase rectangular pulses into two paths of pulses of different loops required for controlling the high-side and low-side transistors respectively, and two paths of output pulses which are not connected in common are respectively kept synchronous with two paths of common-ground input pulses, so that the process is called pulse shunt synchronous conversion. The invention is controlled by two paths of initial pulses which are input in common ground and converted by the shunt circuit. And after the two paths of input common-ground pulses are subjected to delay shaping by a resistance-capacitance RC circuit, the other two paths of synchronous delayed pulses are obtained through shunt conversion to control MOS (metal oxide semiconductor) tubes connected in parallel at two ends of the controllable silicon, and the connected controllable silicon is short-circuited and switched on and then switched off along with the cut-off of the MOS tubes. This control method is also suitable for switching circuits of other configurations, in particular, for full-bridge switching circuits.

The parallel MOS tube not only solves the problem of turn-off of the controllable silicon, but also can share a part of working current of the switch circuit. The high peak current of the switch circuit for charging and discharging capacitive load occurs at the moment when the controllable silicon of the main switch device in the circuit is just switched on, the current peak value can be trailing for a certain time after the current peak value is over, the controllable silicon is equivalent to a forward biased diode after being switched on, the conduction voltage drop is more than 1V when a large current passes, the power loss and the heating are serious, and the delay time for adjusting and controlling the grid control pulse of the parallel MOS tube can also control the power loss shared by the MOS tube. If the MOS tube is switched on too early, the MOS tube is impacted by high peak current, the high peak current capacity of the controllable silicon can not be fully exerted, otherwise, if the switching-on delay time of the MOS tube is too long, the controllable silicon singly bears more continuous power loss, and therefore the MOS tube and the controllable silicon achieve similar working temperature rise and are the best balance point for regulating the switching-on delay time of the MOS tube.

Example 1:

the IR2110 special chip (chip A) of the half-bridge switching circuit carries out shunt conversion on two paths of common-ground input rectangular pulses (initial pulses) to output non-common-ground pulses of a high-end shunt circuit and a low-end shunt circuit, and the two paths of output pulses control a silicon controlled rectifier of the half-bridge circuit. As the two output pulses and the two input pulses are respectively kept synchronous, as shown in figure 3, the input pulses are shaped by a comparator after passing through an RC delay circuit, a pair of delay pulses behind the initial pulses can be formed, the delay pulses are input into another IR2110 half-bridge chip (chip B), the pulses after the output of the chip B is converted by a shunt circuit also generate the same delay as that of the chip A, the output pulses of the chip B control MOS tubes connected in parallel at two ends of a silicon controlled rectifier, and the delay on and off of the MOS tubes can be realized, including the off of the silicon controlled rectifier.

There are various methods for generating the two paths of common-ground opposite-phase rectangular pulses. For example, one method is a circuit that generates a pulse with a certain frequency by using a PWM chip SG3525, as shown in fig. 3, two-way reverse thyristors with a certain duty ratio control the pulse. The two inverted pulses can also be generated by a comparator to generate one pulse and then generate the other inverted pulse through an inverter, or by using a Schmitt trigger chip (such as CD 4583).

The above two pairs of initial pulse and delay pulse can also be directly generated by using a programmable chip such as a microcontroller, and are input into the half-bridge chip after level conversion under different working voltages. The method can accurately adjust the time delay between two paths of pulses and has great flexibility. However, the programmable chip generally has a different working voltage from that of the half-bridge chip and needs a larger working current, and needs to separately supply power to the programmable chip, and meanwhile, the programmable chip is easily interfered in a high-voltage high-current switching circuit, and requires an EMI (electromagnetic interference) prevention design.

Example 2:

the above embodiment 1 can perform reliable delay control on the MOS transistor, but two circuits of the half-bridge chip IR2110 are required to control the thyristor and the MOS transistor respectively, and the circuit is relatively complicated. If the output of a half-bridge chip is used for controlling the controllable silicon, the output pulse is divided into another path for delaying and shaping, and then the delay switch of the MOS tube is controlled, the circuit can be simplified, and the repeated use of the half-bridge chip can be avoided. But the delay-shaping circuit also needs to work with a certain voltage, especially the circuit at the high end of the half-bridge circuit needs to be isolated. However, the method of RC delay + totem pole circuit shown in fig. 4 is adopted, the needed working current is not large, the totem pole circuit is mainly used for accelerating the rising and falling edges of the pulse to reduce the switching loss of the controlled MOS transistor, the high level of the pulse output by the half-bridge chip IR2110 can be supplied with power through a diode and a storage capacitor with proper capacity, the capacity of the storage capacitor is about 20 times of the gate capacitance of the driven MOS transistor, and the output current load capacity of the half-bridge chip is not exceeded, as shown in fig. 4.

The half-bridge circuit high-end MOS tube and the half-bridge circuit low-end MOS tube can respectively adopt the half-bridge chip power supply, RC delay and totem-pole shaped pulse delay circuit in figure 4 to realize delay switch control, and the delay time can be adjusted by selecting proper RC parameters according to the principle that the heat loss and temperature rise shared by the MOS tube and the controlled silicon are the same, so that the cooperative work and the reliability of the two transistors are reasonably ensured.

The invention is not the best known technology.

The above embodiments are merely illustrative of the technical ideas and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the contents of the present invention and implement the present invention, and not to limit the protection scope of the present invention. All equivalent changes and modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.