WO2017080086A1 - Switch bleeder circuit and control method - Google Patents

Abstract

A switch bleeder circuit and a control method. The switch bleeder circuit comprises a first controller, a driver and a freewheeling circuit, wherein the freewheeling circuit comprises a choke inductor, a load and a freewheeling diode; the first controller controls the driver; an output end of the choke inductor is connected to an input end of the load; an output end of the load is connected to an input end of the freewheeling diode; an output end of the freewheeling diode is connected to an input end of the choke inductor; a current input end is provided between the choke inductor and the freewheeling diode; and a current output end is provided between the load and the freewheeling diode; and a bleeder switch is connected in parallel between two ends of the load, and the first controller is connected to the bleeder switch via a second controller. The control method achieves the purpose of whether to short-circuit a load by controlling the on/off of a bleeder switch, thereby realizing current bleeding. By means of the switch bleeder circuit and the control method, a current flowing through a load can be changed to a controllable current without affecting a normal operation and service life of the load.

Description

Switch leakage circuit and control method Technical field

The invention relates to a switch drain circuit and a control method.

Background technique

Figure 1 shows a conventional switching current drive circuit. The AC point V ₁ outputs DC power through the rectifier circuit BD ₁ , the DC power is input to the V ₊ terminal of the current driver, and the DRV terminal of the current driver outputs current to the choke inductor L. , L is the inductance of the choke output is connected to the load input of LED, LED load output is connected to an input terminal of the freewheeling diode D _1, the output terminal of the freewheeling diode D ₁ is connected to an input terminal of a choke inductor L, There is a current output between the load LED and the freewheeling diode D ₁ , and the current output is grounded to GND. PWM controller controls the current driver current driver s V _- is grounded to GND. When the PWM controller outputs a high level 1, the current flowing through the load LED through the choke inductor L reaches the ground GND, the load LED operates, and another portion of the freewheeling current flows through the freewheeling diode D ₁ through the choke inductor L. The loop is formed by the load LED; when the PWM controller changes from the high level 1 to the low level 0, the back electromotive force remaining on the choke inductor L generates a continuous current I _s , and the continuous current I _s passes through the load LED, continued The flow diode D ₁ and the choke inductor L form a loop, that is, a current flows through the load LED. As shown in the current waveform diagram of Figure 2, when the PWM controller is operating at a high level, the current I _LED flowing through the load LED is T ₁ , and there is residual current I _s at the moment when the PWM controller is turned off. ₂ , wherein the current I _s is an extra uncontrollable current, which will affect the illumination and life of the load LED.

An LED linear bleeder circuit and method are disclosed in the patent document No. 201310383613.3, the application date of which is 2013.8.29, the publication date of which is a PWM controller, LED driver IC, inductor and The LED has a drain circuit connected between the inductor and the LED. The method steps are as follows: when the LED is started, the PWM controller turns off the bleed circuit after being reversed. When the PWM controller runs to a low position, the PWM controller starts the bleeder circuit in reverse, and consumes the inductor through the freewheeling tube and the power tube. The resulting freewheeling. Although the circuit describes that it can function as a drain, it does not substantially short-circuit the LED regardless of whether the bleeder circuit is closed or not, that is, whether the PWM controller changes from a high level or a high level. At a low level, the current on the inductor will always pass through the LED, or it will produce a current waveform as shown in Figure 2, that is, a residual current I _s will be generated on the LED, which is uncontrollable.

Also, in the patent document of the patent document No. WO2013055000A1, an LED driving circuit is disclosed, which actually belongs to the existing freewheeling circuit and cannot remove the residual current flowing through the load.

Summary of the invention

In order to make the current flowing through the load into a controllable current without affecting the normal operation and life of the load, the present invention provides a switch drain circuit and a control method.

To achieve the above object, the switch bleeder circuit comprises a first controller, a driver and a freewheeling circuit, the freewheeling circuit comprises a choke inductor, a load and a freewheeling diode; the first controller controls the driver; the output of the choke inductor is connected To the input of the load, the output of the load is connected to the input of the freewheeling diode, the output of the freewheeling diode is connected to the input of the choke inductor, the current input between the choke inductor and the freewheeling diode, the load and There is a current output terminal between the freewheeling diodes; a drain switch is connected in parallel at both ends of the load, and the first controller is connected to the drain switch through the second controller.

The control method of the switch bleeder circuit is: when the first controller outputs a high level, the driver starts to work, the first controller controls the bleed switch to be closed after the second controller, the load works, and a part of the freewheeling current I ₂ The freewheeling diode flows through the choke inductor and then forms a loop through the load; when the first controller changes from a high level to a low level, the driver stops working, and the first controller controls the drain switch after the second controller When turned on, the load is short-circuited. At this time, the back electromotive force remaining on the choke inductor generates a continuous current I _s , and the continuous current I _s is discharged through the freewheeling diode, the choke inductor, and the drain switch.

Further, the first controller is a PWM controller, the second controller is an inverter; the drain switch is a switch MOS transistor Q ₁ , and an output end of the inverter is connected to the switch MOS transistor Q ₁ The G-pole; the PWM controller is connected to the driver and the inverter, the driver is connected to the DC output, the driver is connected to the current input, the output between the load and the freewheeling diode is grounded to GND, and the driver is connected to the GND; When the controller outputs a high level, the PWM controller outputs a low level after the inverter, the switching MOS transistor Q _{1 is} turned off, the current I ₁ flowing through the load through the choke inductor reaches the ground GND, and the other part of the freewheeling current I ₂ After the freewheeling diode flows through the choke inductor and then forms a loop through the load; when the PWM controller changes from a high level to a low level, the PWM controller outputs a high level after the inverter, and the switch MOS transistor Q ₁ When turned on, the load is short-circuited. At this time, the back electromotive force remaining on the choke inductor generates a continuous current I _s , and the continuous current I _s is discharged through the freewheeling diode, the choke inductor, and the switching MOS transistor Q ₁ .

Further, the first controller is a PWM controller, the second controller is an inverter; the drain switch is a switch MOS transistor Q ₁ , and an output end of the inverter is connected to the switch MOS transistor Q ₁ On the G pole; the PWM controller is connected to the driver and the inverter; the driver is connected to the DC output, the DC output is connected to the current input, and the driver is connected to the G pole of the MOS transistor Q ₂ , between the load and the freewheeling diode The output terminal is grounded to GND via MOS transistor Q ₂ , and the driver is connected to GND. When the PWM controller outputs a high level, the PWM controller outputs a low level after the inverter, and the switching MOS transistor Q _{1 is} turned off, and the MOS transistor Q _{2 is} turned off. Turn on, the current I ₁ flowing through the load through the choke inductor passes through the MOS transistor Q ₂ to the ground GND, and the other part of the freewheeling current I ₂ flows through the choke inductor through the freewheeling diode and then forms a loop through the load; when the PWM controller At the moment when the high level changes to the low level, the PWM controller outputs a high level after the inverter, the switching MOS transistor Q _{1 is} turned on, the load is short-circuited, and the MOS transistor Q _{2 is} turned on. At this time, the residual current is in the choke inductor. The back electromotive force on the generated continuous current I _s , the continuous current I _s through the freewheeling diode, 扼The flow inductor and the switching MOS transistor Q _{1 are} vented.

The beneficial effects of the present invention are: when the first controller outputs a high level, a current I ₁ is generated on the load, the current is controllable, and the current required by the load is changed from the high level to the first controller. At the moment of low level, since the drain switch is turned on, the load is short-circuited. Therefore, during this period of time, the residual current remaining in the choke inductor is never passed, and the residual current is discharged. Therefore, regardless of the operating state of the first controller, the current flowing through the load is controllable and does not affect the normal operation and life of the load.

DRAWINGS

1 is a schematic diagram of a prior art switching current drive circuit.

2 is a current waveform diagram of a prior art switching current drive circuit.

Figure 3 is a control logic diagram of the present invention.

4 is a circuit diagram of a switch drain circuit according to Embodiment 1 of the present invention.

FIG. 5 is a schematic diagram of a PWM controller of a switching bleeder circuit according to Embodiment 1 of the present invention when a high level is output.

6 is a schematic diagram of the PWM controller of the switching bleeder circuit of the first embodiment of the invention changing from a high level to a low level.

Figure 7 is a circuit diagram of a switching drain circuit of Embodiment 2 of the present invention.

Fig. 8 is a current waveform diagram of the switch bleeder circuit of the present invention.

detailed description

The present invention will be further described in detail below in conjunction with the drawings and specific embodiments.

Example 1.

As shown in FIG. 3, the switch bleeder circuit includes a first controller, a driver, a freewheeling circuit, and a bleeder circuit.

As shown in Figures 3 and 4, the first controller is a PWM controller. The driver is a current driver U ₁ , and the current driver U ₁ has an input terminal V ₊ and a PWM input terminal and output terminals DRV and V ₋ . PWM input end of the AC power source V ₁ via the rectifier circuit BD ₁ into DC current input to the driver input terminal V U ₁ is _+, PWM control signal is input to a current driver U _1, the current driver input V U ₁ is _- Ground To GND.

The freewheeling circuit comprises a choke inductor L, the load and LED _1, the output terminal of the choke inductance L freewheeling diode D is connected to the load input of LED, LED load output connected to the input of _a freewheeling diode D The output terminal of the freewheeling diode D ₁ is connected to the input end of the choke inductor L, the current input terminal is connected between the choke inductor L and the freewheeling diode D ₁ , and the current input terminal is connected to the output terminal DRV of the current driver U ₁ . , LED load and the freewheeling diode having a current output terminal D _1, the current output terminal is grounded to the GND, while being connected to the rectifier circuit BD _1.

The bleeder circuit includes a second controller and a bleeder switch, the second controller is an inverter U ₂ , the bleeder switch is a switch MOS transistor Q ₁ , and the PWM controller is connected to the switch MOS via an inverter U ₂ The G pole of the tube is connected in parallel with the switching MOS transistor Q ₁ at both ends of the load LED.

The control method of the above switch bleed circuit is as follows: as shown in FIG. 5, when the PWM controller outputs a high level 1, the PWM controller outputs a low level after the inverter U ₂ , and the switch MOS transistor Q _{1 is} turned off. The choke inductor L flows through the current I ₁ portion of the load LED to the ground GND, and the other portion of the freewheeling current I ₂ flows through the choke inductor L through the freewheeling diode D ₁ and then forms a loop through the load LED. As shown in FIG. 6, when the PWM controller changes from a high level to a low level, the PWM controller outputs a high level after the inverter U ₂ , the switch MOS transistor Q _{1 is} turned on, and the load LED is short-circuited. At this time, the back electromotive force remaining on the choke inductor L generates a continuous current I _s , and the continuous current I _s is discharged through the freewheeling diode D ₁ , the choke inductor L and the switching MOS transistor Q ₁ .

As shown in Figure 8, when the PWM controller outputs a high level, a current I ₁ is generated on the load LED, that is, the time that the I _{LED is} generated is T ₁ , which is controllable and is the current required to load the LED. When the PWM controller changes from a high level to a low level, since the switching MOS transistor Q ₁ is turned on, the load LED is short-circuited. Therefore, during this period of time, the load LED will never have residual residuals of the choke inductor. current, see Figure 8, after time T ₁ has no current waveform, and the residual current will vent out. Therefore, regardless of the operating state of the PWM controller, the current flowing through the load LED is controllable and does not affect the normal operation and life of the load.

Example 2.

As shown in FIG. 3, the switch bleeder circuit includes a first controller, a driver, a freewheeling circuit, and a bleeder circuit.

As shown in Figures 3 and 7, the first controller is a PWM controller. The driver is a current driver U ₁ , and the current driver U ₁ has an input terminal V ₊ and a PWM input terminal and output terminals DRV and V ₋ . AC power source V ₁ via the rectifier circuit BD ₁ into DC current input to the driver U input terminal V _{1 +} and simultaneously input directly into the choke inductor L through the DC rectifier BD ₁ is, PWM control signal is input to the current driver U PWM input terminal _1, the current driver input terminal V U _{1 -} is grounded to the GND, the output terminal of the current driver DRV is connected to the MOS transistor Q G ₂ pole.

The freewheeling circuit comprises a choke inductor L, the load and LED _1, the output terminal of the choke inductance L freewheeling diode D is connected to the load input of LED, LED load output connected to the input of _a freewheeling diode D The output terminal of the freewheeling diode D ₁ is connected to the input end of the choke inductor L, the current input terminal is connected between the choke inductor L and the freewheeling diode D ₁ , and the current input terminal is connected to the output terminal DRV of the current driver U ₁ . , LED load and the freewheeling diode D ₁ having a current output terminal, the output terminal of the current through the MOS transistor Q ₂ is grounded to the GND, while being connected to the rectifier circuit BD _1.

The bleeder circuit includes a second controller and a bleeder switch, the second controller is an inverter U ₂ , the bleeder switch is a switch MOS transistor Q ₁ , and the PWM controller is connected to the switch MOS via an inverter U ₂ The G pole of the tube is connected in parallel with the switching MOS transistor Q ₁ at both ends of the load LED.

The control method of the above switch bleed circuit is: when the PWM controller outputs a high level 1, the PWM controller outputs a low level after the inverter U ₂ , the switch MOS transistor Q _{1 is} turned off, and the MOS transistor Q _{2 is} turned on. The current I ₁ flowing through the load LED of the choke inductor L passes through the MOS transistor Q ₂ to the ground GND, and the other portion of the freewheeling current I ₂ flows through the choke inductor L through the freewheeling diode D ₁ and then forms a loop through the load LED. When the PWM controller changes from high level to low level, the PWM controller outputs a high level after the inverter U ₂ , the switch MOS transistor Q _{1 is} turned on, the MOS transistor Q _{2 is} turned on, and the load LED is short-circuited. At this time, the back electromotive force remaining on the choke inductor L generates a continuous current I _s , and the continuous current I _s is discharged through the freewheeling diode D ₁ , the choke inductor L and the switching MOS transistor Q ₁ .

As shown in Figure 8, when the PWM controller outputs a high level, a current I ₁ is generated on the load LED, that is, the time that the I _{LED is} generated is T ₁ , which is controllable and is the current required to load the LED. When the PWM controller changes from a high level to a low level, since the switching MOS transistor Q ₁ is turned on, the load LED is short-circuited. Therefore, during this period of time, the load LED will never have residual residuals of the choke inductor. current, see Figure 8, after time T ₁ has no current waveform, and the residual current will vent out. Therefore, regardless of the operating state of the PWM controller, the current flowing through the load LED is controllable and does not affect the normal operation and life of the load.

Claims (7)

1. The switch bleeder circuit comprises a first controller, a driver and a freewheeling circuit, the freewheeling circuit comprises a choke inductor, a load and a freewheeling diode; the first controller controls the driver; the output of the choke inductor is connected to the input of the load The output of the load is connected to the input of the freewheeling diode. The output of the freewheeling diode is connected to the input of the choke inductor. The current input between the choke inductor and the freewheeling diode is between the load and the freewheeling diode. The utility model has a current output terminal, which is characterized in that: a drain switch is connected in parallel at both ends of the load, and the first controller is connected to the drain switch through the second controller.
2. The switch bleeder circuit of claim 1 wherein said first controller is a PWM controller and said second controller is an inverter.
3. The switch bleeder circuit according to claim 2, wherein the PWM controller is connected to the driver and the inverter, the driver is connected to the DC output terminal, the driver is connected to the current input terminal, and the output terminal between the load and the freewheeling diode is connected. Grounded to GND, the driver is connected to GND; the drain switch is the switching MOS transistor Q ₁ , and the output of the inverter is connected to the G pole of the switching MOS transistor Q ₁ .
4. The switch bleeder circuit according to claim 2, wherein the PWM controller is connected to the driver and the inverter; the driver is connected to the DC output terminal, the DC output terminal is connected to the current input terminal, and the driver is connected to the MOS transistor Q ₂ On the G pole, the output between the load and the freewheeling diode is grounded to GND via MOS transistor Q ₂ , and the driver is connected to GND; the drain switch is a switching MOS transistor, and the output of the inverter is connected to the switching MOS transistor On the G pole.
5. The control method of the switch bleeder circuit is characterized in that: when the first controller outputs a high level, the driver starts to work, the first controller controls the bleed switch to be closed after the second controller, the load works, and a part of the freewheeling current After the I ₂ flows through the choke inductor and then flows through the load to form a loop; when the first controller changes from a high level to a low level, the driver stops working, and the first controller is controlled by the second controller. The drain switch is opened and the load is shorted. At this time, the back electromotive force remaining on the choke inductor generates a continuous current I _s , and the continuous current I _s is discharged through the freewheeling diode, the choke inductor and the drain switch.
6. The control method of the switch bleeder circuit according to claim 5, wherein the first controller is a PWM controller, the second controller is an inverter, and the bleed switch is a switch MOS tube. Q ₁ , the output of the inverter is connected to the G pole of the switching MOS transistor Q ₁ ; the PWM controller is connected to the driver and the inverter, the driver is connected to the DC output terminal, the driver is connected to the current input terminal, and the load and the freewheeling diode are connected. The output is grounded to GND, and the driver is connected to GND. When the PWM controller outputs a high level, the PWM controller outputs a low level after the inverter, the switching MOS transistor Q _{1 is} turned off, and the choke inductor flows through the load. The current I ₁ part is to the ground GND, and the other part of the freewheeling current I ₂ flows through the choke inductor through the freewheeling diode and then forms a loop through the load; when the PWM controller changes from a high level to a low level, the PWM control After the inverter outputs a high level, the switching MOS transistor Q _{1 is} turned on, and the load is short-circuited. At this time, the back electromotive force remaining on the choke inductor generates a continuous current I _s , and the continuous current I _s flows through the freewheeling diode, The choke inductor and the switching MOS transistor Q _{1 are} vented.
7. The control method of the switch bleeder circuit according to claim 5, wherein the first controller is a PWM controller, the second controller is an inverter, and the bleed switch is a switch MOS tube. Q ₁ , the output of the inverter is connected to the G pole of the switching MOS transistor Q ₁ ; the PWM controller is connected to the driver and the inverter; the driver is connected to the DC output terminal, the DC output terminal is connected to the current input terminal, and the driver is connected to the driver _On the G pole of the MOS transistor Q ₂ , the output terminal between the load and the freewheeling diode is grounded to the GND via the MOS transistor Q ₂ , and the driver is connected to the GND; when the PWM controller outputs a high level, the PWM controller is passed through the inverter When the output is low, the switch MOS transistor Q _{1 is} turned off, the MOS transistor Q _{2 is} turned on, the current I ₁ flowing through the load through the choke inductor is passed through the MOS transistor Q ₂ to the ground GND, and the other portion of the freewheeling current I ₂ is passed through the freewheeling diode. After flowing through the choke inductor, the circuit is formed by the load; when the PWM controller changes from high level to low level, the PWM controller outputs a high level after the inverter, and the switch MOS tube Q _{1 is} turned on, and the load is short circuit, the MOS tube Q ₂ is opened, this time, on a residual reverse current choke inductor Potential produce sustained current I _s, I _s continuous current through the freewheeling diode, a choke inductor, and a switch MOS transistor Q ₁ exhausting.

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