CN102883511B - Multi-path series-parallel LED (light-emitting diode) load fault protection driving circuit and fault diagnosis and protection method - Google Patents

Abstract

The invention discloses a multi-channel series-parallel LED load fault protection drive circuit and an LED load fault diagnosis and protection method. By adding the second primary side winding of the transformer and a load fault judgment control unit, when an LED load fault occurs, the transformer's first The two primary windings feed back the voltage change signal at the output of the drive circuit to the load fault judgment control unit, the load fault judgment control unit will reduce the output to reduce the reference voltage output signal of the voltage reference chip, and control the output of the drive module to Reduce the output current of the drive circuit to protect the remaining LED loads to work normally. Compared with the prior art, the present invention efficiently controls and protects other non-faulty LED light sources under the existing LED connection conditions, and has lower cost and better economic benefits.

Description

Multi-channel series-parallel LED load fault protection driving circuit and fault diagnosis and protection method

technical field

The invention relates to the field of LED electronic applications, in particular to a multi-channel series-parallel LED load fault protection driving circuit and a multi-channel series-parallel LED load fault diagnosis and protection method.

Background technique

With the development of lighting technology, LED light source, as a new green light source, is gaining more and more development, and the application of LED is becoming a future trend. In many LED application technologies, except for some special occasions, the connection methods of LEDs are basically connected in series and parallel. Even the newly emerging COB packaging, its internal structure also adopts these methods. . This connection method will have great benefits for the application of LEDs, but it also brings some other disadvantages.

For example, as shown in Figure 1, since the LEDs are connected in series and parallel, in the actual use process, if one LED in a single string of LEDs fails, such as an open circuit and blown (short circuit may also occur, but after the LED is short circuited, Due to the large current passing through, the LED will be blown by the high current in a short time, and the final failure phenomenon is also an open circuit). Since the LED drive is in a constant current state, for other LEDs of this load, the current on it will increase accordingly (as shown in the 2nd and 3rd circuits of Figure 1, the increase is equal to the current flowing through the 1st channel. Now it is evenly distributed to 2 roads and 3 roads). In this case, it is extremely easy to cause damage to the 2-way and 3-way LEDs.

In the prior art, in response to such a situation, the LED drive power supply on the market has also been adjusted, that is, the output of one LED driver is multiple outputs, which supply power to LEDs of 1, 2, and 3 respectively. Even if there is a problem with one LED light source, it will not affect the other two, which ensures the normal operation of the LED and prevents the occurrence of the above-mentioned vicious circle phenomenon.

Although the general LED driver on the market now solves the LED light source series and parallel method, it avoids damage to other parallel LED light sources when the LED light source fails, and the problem has been greatly improved. greatly improved. Not to mention the increased cost of implementing several outputs on the circuit, the output wire alone has increased from the original single wire to three. Therefore, the method for solving this problem in the prior art has the disadvantage of greatly increasing the cost.

Contents of the invention

In view of the deficiencies in the prior art, the technical problem to be solved by the present invention is to provide a multi-channel series-parallel LED load fault protection driving circuit and a fault diagnosis and protection method. When one of the multi-channel series-parallel LED loads fails , can judge the failure in time and reduce the output current of the drive circuit to protect other LED loads from working normally. the

The technical solution provided by the present invention is a multi-channel series-parallel LED load fault protection drive circuit, including a rectifier circuit and a drive module connected to the first primary winding of the transformer, and a voltage reference chip connected to the output end of the drive circuit, Also includes:

The second primary winding of the transformer is used to feed back the signal of the voltage rise of the secondary side to the primary side when the load fails;

A load fault judgment control unit, the load fault judgment control unit is respectively connected to the first primary winding and the second primary winding of the transformer, and is used to judge whether a load fault occurs and to control the input signal of the voltage reference chip;

The load fault judgment control unit is connected to the drive module, and when it is judged that a load fault occurs, the second primary winding of the transformer feeds back a fault signal to the load fault judgment control unit, and the load fault judgment control unit will The reference voltage output signal of the voltage reference chip is changed, and the output of the driving module is controlled to reduce the output current of the driving circuit.

Preferably, the load fault judgment control unit includes an MCU micro control unit.

Preferably, the MCU micro control unit changes the duty ratio of the MOS transistor to reduce the output current of the driving circuit.

Preferably, a first optocoupler and a second optocoupler are connected between the MCU micro control unit and the voltage reference chip, and the signal transmission directions of the first optocoupler and the second optocoupler are opposite.

Preferably, the fault signal is a voltage change signal at the output terminal of the drive circuit.

The present invention also provides a multi-channel series-parallel LED load fault diagnosis and protection method. The multi-channel series-parallel LED load fault protection drive circuit includes a rectifier circuit and a drive module connected to the first primary winding of the transformer, and a drive module connected to the drive circuit. A voltage reference chip at the output end, adding a second primary winding on the primary side of the transformer, for feeding back the signal of the voltage rise of the secondary side to the primary side when the load fails;

Adding a load fault judgment control unit respectively connected to the first primary winding and the second primary winding of the transformer, the load fault judgment control unit is used to judge whether a load fault occurs and to control the input signal of the voltage reference chip;

The load fault judgment control unit is connected with the drive module, and when a load fault occurs, the second primary winding of the transformer feeds back a fault signal to the load fault judgment control unit, and the load fault judgment control unit passes After it is judged as a load fault, the reference voltage output signal of the voltage reference chip will be adjusted, and the adjusted reference voltage output signal is input to the load fault judgment control unit, and the output of the drive module is controlled by the load fault judgment control unit to reduce The output current of the drive circuit.

Preferably, the fault signal is a voltage change signal at the output terminal of the drive circuit.

Preferably, the load fault judgment control unit is an MCU micro control unit.

Preferably, the MCU micro control unit changes the duty ratio of the MOS transistor to reduce the output current of the driving circuit.

Preferably, a first optocoupler and a second optocoupler are connected between the MCU micro-control unit and the voltage reference chip, and when a load fault occurs, the output signal of the load fault judgment control unit is input to the voltage via the second optocoupler The reference chip is used to adjust the reference voltage output signal, and the adjusted reference voltage output signal is input to the load fault judgment control unit through the first optocoupler.

Compared with the prior art, the present invention has the advantages that: the present invention increases the second primary side winding of the transformer and the load fault judging control unit, when the LED load fault occurs, the output voltage of the LED drive circuit changes through the second primary The side winding is fed back to the load fault judgment control unit, and the load fault judgment control unit reduces the output current of the drive circuit after judging that it is a fault. Compared with the prior art, the present invention efficiently controls and protects other non-faulty LED light sources under the existing LED connection conditions, and has lower cost and better economic benefits.

Description of drawings

Accompanying drawing 1 is a multi-channel series-parallel LED load fault protection driving circuit in the prior art;

Accompanying drawing 2 is the multi-channel series-parallel LED load failure protection driving circuit of the present invention;

Detailed ways

Below in conjunction with accompanying drawing, the present invention is described in further detail:

As shown in Figure 2, a multi-channel series-parallel LED load fault protection drive circuit, the input end of the drive circuit is connected to the mains, and the output end is connected to the multi-channel series-parallel LED load. The drive circuit includes a rectifier circuit and a drive module connected to the first primary winding of the transformer, a voltage reference chip connected to the output end of the drive circuit, and a second primary winding of the transformer, which is used to switch the secondary The signal of voltage rise is fed back to the primary side;

A load fault judgment control unit, the load fault judgment control unit is respectively connected to the first primary winding and the second primary winding of the transformer, and is used to judge whether a load fault occurs and to control the input signal of the voltage reference chip;

The load fault judging control unit is connected with the drive module. When it is judged that an LED load fault occurs, the second primary winding of the transformer feeds back the voltage change signal at the output end of the drive circuit to the load fault judging control unit, and the load fault judging control unit will Adjust the reference voltage output signal of the voltage reference chip, and control the output of the drive module to reduce the output current of the drive circuit, so as to protect the normal operation of the remaining LED loads.

In this embodiment, the load fault judgment control unit is an MCU micro control unit. The MCU micro control unit reduces the output current of the drive circuit by changing the duty cycle of the MOS tube.

A first optocoupler and a second optocoupler are connected between the MCU micro control unit and the voltage reference chip, and the signal transmission directions of the first optocoupler and the second optocoupler are opposite.

The present invention also provides a multi-channel series-parallel LED load fault diagnosis and protection method. The multi-channel series-parallel LED load fault protection drive circuit includes a rectifier circuit and a drive module connected to the first primary winding of the transformer, and a drive module connected to the drive circuit. The voltage reference chip at the output end adds a second primary winding to the primary side of the transformer, which is used to feed back the signal of secondary voltage rise when the load fails to the primary side and input it to the MCU micro control unit.

An MCU micro-control unit connected to the first primary winding and the second primary winding of the transformer is also added, and the MCU micro-control unit is used to judge whether an LED load fault occurs and to control the input signal of the voltage reference chip .

The load fault judgment control unit is connected with the drive module, and when an LED load fault occurs, the second primary winding of the transformer feeds back the voltage change signal at the output end of the drive circuit to the MCU micro control unit, and the MCU micro control unit passes After the calculation and comparison determine that the load is faulty, the reference voltage output signal of the voltage reference chip will be adjusted, and the reference voltage output signal will be input to the MCU micro control unit, and the MCU micro control unit will control the output of the drive module to reduce the output current of the drive circuit.

In this embodiment, the MCU micro control unit changes the duty cycle of the MOS transistor to reduce the output current of the driving circuit.

A first optocoupler and a second optocoupler are connected between the MCU micro-control unit and the voltage reference chip. When a load fault occurs, the output signal of the load fault judgment control unit is input to the voltage reference chip through the second optocoupler to adjust the reference The voltage output signal and the adjusted reference voltage output signal are input to the load fault judgment control unit through the first optocoupler.

In the present invention, by adding the second primary winding of the transformer and the load fault judgment control unit, when the LED load fault occurs, the output voltage change of the LED drive circuit is fed back to the load fault judgment control unit through the second primary winding, and the load fault The judging control unit reduces the output current of the drive circuit after judging that it is a fault. Compared with the prior art, the present invention efficiently controls and protects other non-faulty LED light sources under the existing LED connection conditions, and has lower cost and better economic benefits.

The present invention also can have other various embodiments, without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and deformations according to the present invention, but these corresponding changes and deformations should be Belong to the protection scope of the claims of the present invention.

Claims (8)

1. A multi-channel series-parallel LED load fault protection drive circuit, comprising a rectifier circuit connected to the first primary winding of the transformer and a drive module, a voltage reference chip connected to the output of the drive circuit, characterized in that it also includes : The second primary winding of the transformer is used to feed back the signal of the voltage rise of the secondary side to the primary side when the load fails; MCU micro control unit, the MCU micro control unit is connected with the second primary winding of the transformer, and is used for judging whether a load fault occurs and controlling the input signal of the voltage reference chip; The MCU micro control unit is connected with the drive module, and when it is judged that a load fault occurs, the second primary winding of the transformer will feed back the fault signal to the MCU micro control unit, and the MCU micro control unit will adjust the voltage reference The reference voltage of the chip, and control the output of the driving module to reduce the output current of the driving circuit. 2. A multi-channel series-parallel LED load fault protection drive circuit according to claim 1, characterized in that: the MCU micro control unit changes the duty ratio of the MOS transistor to reduce the output current of the drive circuit. 3. A multi-channel series-parallel LED load fault protection driving circuit according to claim 2, characterized in that: a first optocoupler and a second optocoupler are connected between the MCU micro control unit and the voltage reference chip, Signal transmission directions of the first optocoupler and the second optocoupler are opposite. 4. A multi-channel series-parallel LED load fault protection drive circuit according to claim 1, wherein the fault signal is a voltage change signal at the output end of the drive circuit. 5. A multi-channel series-parallel LED load fault diagnosis and protection method, the multi-channel series-parallel LED load fault protection drive circuit includes a rectifier circuit and a drive module connected to the first primary winding of the transformer, and a voltage at the output end of the drive circuit The reference chip is characterized in that a second primary winding is added to the primary side of the transformer to feed back the signal of the voltage rise of the secondary side to the primary side when the load fails; An MCU micro-control unit connected to the second primary winding of the transformer is added, and the MCU micro-control unit is used to judge whether a load fault occurs and to control the input signal of the voltage reference chip; The MCU micro-control unit is connected with the drive module, and when a load fault occurs, the second primary winding of the transformer feeds back the fault signal to the MCU micro-control unit, and the MCU micro-control unit is judged as a load After the failure, the reference voltage of the voltage reference chip will be adjusted, and the adjusted reference voltage output signal is input to the MCU micro control unit, and the MCU micro control unit controls the output of the drive module to reduce the output current of the drive circuit. 6. A method for fault diagnosis and protection of multi-channel series-parallel LED loads according to claim 5, wherein the fault signal is a voltage change signal at the output end of the drive circuit. 7. A method for fault diagnosis and protection of multi-channel series-parallel LED loads according to claim 5, characterized in that: said MCU micro control unit changes the duty cycle of the MOS transistor to reduce the output current of the drive circuit. 8. A multi-channel series-parallel LED load fault diagnosis and protection method according to claim 7, characterized in that: a first optocoupler and a second optocoupler are connected between the MCU micro control unit and the voltage reference chip, When a load failure occurs, the output signal of the MCU micro-control unit is input to the voltage reference chip through the second optocoupler to adjust the reference voltage output signal, and the adjusted reference voltage output signal is input to the MCU micro-control unit through the first optocoupler .