CN210780559U - Single-stage double-cut type wide input range power supply conversion circuit - Google Patents

Abstract

A single-order double-cutting type wide-input-range power conversion circuit comprises a power input end, a switching node, a transformer, two electronic switches, a pulse width modulation circuit and an output circuit, wherein the input side of the transformer comprises a first winding and a second winding which are connected with the switching node, the output side of the transformer comprises an output winding, the turn ratio of the first winding to the output winding is different from that of the second winding to the output winding, the two electronic switches are respectively connected with the first winding and the second winding in series and respectively provided with a control end, the detection end of the pulse width modulation circuit is connected with the power input end, two signal output ends of the pulse width modulation circuit are respectively connected with the control ends of the two electronic switches, and the output circuit is connected with the output winding of the transformer; the utility model discloses utilize two kinds of turns ratio to supply the operation at extremely wide input voltage scope.

Description

Single-stage double-cut wide input range power conversion circuit

technical field

The utility model relates to a power conversion circuit, in particular to a single-stage double-cut type wide input range power conversion circuit.

Background technique

Please refer to FIG. 4 , the prior art wide input range power conversion circuit includes a power input terminal 60 , a buck circuit 61 , a transformer 62 , an output circuit 63 , and a pulse width modulation (PWM) controller 64 , a feedback circuit 65 and an electronic switch Q.

The power input terminal 60 is for receiving an input voltage VIN, the step-down circuit 61 is connected between the power input terminal 60 and the coil winding of the input side (primary side) of the transformer 62 , and the output circuit 63 is connected to the output of the transformer 62 Between the side (secondary side) coil winding and a power output terminal 630, the electronic switch Q is connected in series with the input side coil winding of the transformer 62 and has a control terminal, and the output terminal of the PWM controller 64 is connected to the electronic switch Q The control terminal drives the electronic switch Q with an output PWM signal. Generally speaking, the PWM controller 64 can perform pulse width modulation according to the current of the coil winding on the input side of the transformer 62 and/or the output voltage Vo of the power output terminal 630 . In the example shown in FIG. 4 , the feedback circuit 65 is connected to Between the power output terminal 630 and the input terminal of the PWM controller 64, the PWM controller 64 obtains the magnitude of the output voltage Vo.

However, the wide input range power conversion circuits in the prior art include the following disadvantages:

1. The step-down circuit 61 is used as a first-stage voltage regulator, and the transformer 62 is used as a second-stage isolation. Therefore, the power conversion circuit in the prior art is a two-stage mode, which requires two power conversions, resulting in The power conversion efficiency cannot be effectively improved.

2. The turns ratio of the input side coil winding and the output side coil winding of the transformer 62 is single and fixed, so the duty cycle performance of the transformer 62 is limited. For example, when an extremely wide input voltage range (eg, a range of 9 volts to 160 volts) is used in the prior art wide input range power conversion circuit, the performance of the transformer 62 for lower input voltages and higher input voltages Poor, that is, the energy cannot be effectively transmitted from the power input terminal VIN to the power output terminal 630 , resulting in the application of a wide input voltage range, its efficiency cannot achieve an ideal performance.

Utility model content

The main purpose of the present invention is to provide a single-stage double-cut type wide input range power conversion circuit, in order to overcome the inability to effectively improve the power conversion efficiency of the wide input range power conversion circuit in the prior art, and for the extremely wide input voltage range Among them, lower input voltages and higher input voltages have poorer performance technical issues.

The single-stage double-cut type wide input range power conversion circuit of the utility model comprises:

a power input terminal;

a switching node, connected to the power input;

A transformer has an input side and an output side, the input side includes a first winding and a second winding connected to the switching node, the output side includes an output winding, wherein the first winding and the output winding are a turns ratio different from the turns ratio of the second winding and the output winding;

a first electronic switch, connected in series with the first winding and having a control terminal;

a second electronic switch, connected in series with the second winding and having a control terminal;

A pulse width modulation (PWM) circuit, including a comparison unit and a PWM controller, the comparison unit has a detection terminal, a voltage switching point setting terminal, a PWM input terminal, a first signal output terminal and a second a signal output end, the detection end is connected to the power input end, the first signal output end is connected to the control end of the second electronic switch, the second signal output end is connected to the control end of the first electronic switch; A PWM output is connected to the PWM input of the comparison unit; and

An output circuit is connected to the output winding of the transformer and includes a power output terminal.

Compared with the power conversion circuit in the prior art, the effect of the utility model is as follows:

1. The input side of the transformer of the present utility model is connected to the power input terminal through a switching node, and there is no first-order voltage regulation of the power conversion circuit in the prior art, so the present utility model is a one-stage double-cut (one-stage) two-switch) circuit structure, its power conversion efficiency can be improved.

2. Different from the transformer of the power conversion circuit in the prior art, which only has a single and fixed turns ratio, the input side of the transformer of the present invention includes a first winding and a second winding, and the turns ratio of the first winding and the output winding is Different from the turns ratio of the second winding to the output winding. It can be seen that with two different turns ratios, the present invention can be operated in a very wide input voltage range. For example, the turns ratio of the first winding and the output winding can be applied in a lower input voltage range. , the turns ratio of the second winding to the output winding can be applied in the higher input voltage range. On the whole, the lower input voltage range and the higher input voltage range are combined into an extremely wide input voltage range, so the present invention can operate in an extremely wide input voltage range and maintain ideal power conversion efficiency.

Description of drawings

1 is a schematic circuit diagram of an embodiment of a single-stage double-cut wide input range power conversion circuit of the present invention;

Fig. 2 is the circuit schematic diagram of the pulse width modulation circuit in the utility model;

3 is a schematic diagram of the signal timing sequence of the utility model;

FIG. 4 is a schematic diagram of a wide input range power conversion circuit in the prior art.

Detailed ways

Please refer to FIG. 1 and FIG. 2 , the embodiment of the single-stage double-cut wide input range power conversion circuit of the present invention includes a power input terminal 10 , a switching node 20 , a transformer T1 , a first electronic switch Q1 , and a first electronic switch Q1 . Two electronic switches Q2 , a pulse width modulation (PWM) circuit 30 and an output circuit 40 . Wherein, the circuit structure of the embodiment of the present invention takes a forward circuit as an example, but is not limited to this, for example, it can also be applied to a flyback circuit or a push-pull circuit .

The power input terminal 10 is connected to the previous stage circuit to receive a DC input voltage (+VIN). For example, the voltage range of the input voltage (+VIN) can reach an extremely wide input voltage range of 9V to 160V. The switching node 20 is connected to the power input terminal 10 . In the embodiment of the present invention, the switching node 20 can be directly connected to the power input terminal 10 .

The transformer T1 includes an input side (primary side) and an output side (secondary side), the input side includes a first winding Np1 and a second winding Np2 connected to the switching node 20 , and the output side includes an output winding Ns, wherein the number of turns of the first winding Np1 and the second winding Np2 are different, so the turns ratio of the first winding Np1 and the output winding Ns is different from the turns ratio of the second winding Np2 and the output winding Ns number ratio. The input terminal of the output circuit 40 is connected to the output winding Ns, and the output circuit 40 includes a power output terminal 41 . As shown in FIG. 1 , one end of the first winding Np1 is directly connected to the switching node 20, and one end of the second winding Np2 is connected to the switching node 20 through a backflow preventing element D1. In the embodiment of the present invention, the backflow preventing The element D1 is a diode, the anode of the diode is connected to the switching node 20, and the cathode of the diode is connected to the second winding Np2.

The first electronic switch Q1 is connected in series with the first winding Np1. In the embodiment of the present invention, the first electronic switch Q1 has a first terminal, a second terminal and a control terminal, and the first terminal is connected to the first terminal. The other end of a winding Np1. For example, the first electronic switch Q1 can be an N-type metal oxide semiconductor field effect transistor (n-MOSFET), the first terminal is a drain (Drain), the second terminal is a source (Source), the The control terminal is the gate (Gate).

The second electronic switch Q2 is connected in series with the second winding Np2. In the embodiment of the present invention, the second electronic switch Q2 has a first terminal, a second terminal and a control terminal, and the first terminal is connected to the first terminal. The other end of the secondary winding Np2. For example, the second electronic switch Q2 can be an N-type metal oxide semiconductor field effect transistor (n-MOSFET), the first terminal is a drain (Drain), the second terminal is a source (Source), the The control terminal is the gate (Gate). As shown in FIG. 1 , the second terminal of the first electronic switch Q1 is connected to the second terminal of the second electronic switch Q2 to form a connection node 21 , and the connection node 21 can be connected to a current detection circuit 50 .

1 and FIG. 2, the pulse width modulation circuit 30 can be an integrated circuit device (Integrated Circuit, IC), which includes a comparison unit 31 and a PWM controller 32, the comparison unit 31 has a detection terminal DET, a The voltage switching point setting terminal Vset, a PWM input terminal 310, a first signal output terminal OUT1 and a second signal output terminal OUT2. The detection terminal DET is connected to the power input terminal 10 to detect the magnitude of the input voltage. In the embodiment of the present invention, the detection terminal DET is connected to the power input terminal 10 through a voltage divider circuit 33; the first signal output terminal OUT1 is connected to The control terminal of the second electronic switch Q2; the second signal output terminal OUT2 is connected to the control terminal of the first electronic switch Q1; in the embodiment of the present invention, the PWM controller 32 can be a current mode (current mode) The PWM controller has a PWM output terminal 320, the PWM output terminal 320 is connected to the PWM input terminal 310 of the comparison unit 31, an input terminal CS of the PWM controller 32 is connected to the current detection circuit 50, and the PWM controller 32 The other input terminal COMP is connected to the power output terminal 41 of the output circuit 40 through a feedback circuit 51 ; therefore, the PWM controller 32 performs current and voltage detection based on the current detection circuit 50 and the feedback circuit 51 . The pulse width is modulated, and a PWM signal is output at the PWM output end 320 , and the comparison unit 31 receives the PWM signal.

Referring to FIG. 2 , the comparison unit 31 includes a comparator 34 , an inverter 35 , a first driver 36 and a second driver 37 . The comparator 34 has a positive input terminal (+), a negative input terminal (-) and an output terminal VC1. A resistor R8 is connected between the positive input terminal (+) and the output terminal VC1 to provide a hysteresis function, wherein , the positive input terminal (+) is the detection terminal DET, the negative input terminal (-) is the voltage switching point setting terminal Vset; the input terminal of the inverter 35 is connected to the output terminal VC1 of the comparator 34 ; The first driver 36 has an enable terminal EN1, an input terminal S and the first signal output terminal OUT1, and the enable terminal EN1 of the first driver 36 is connected to the input terminal of the inverter 35; the second driver 37 has an enable terminal EN2, an input terminal S and the second signal output terminal OUT2, the enable terminal EN2 of the second driver 37 is connected to the output terminal of the inverter 35, and the input terminal S of the second driver 37 Connecting to the input terminal of the first driver 36 , the input terminal S of the first driver 36 or the second driver 37 can be used as the PWM input terminal 310 for connecting to the PWM output terminal 320 of the PWM controller 32 .

In the first driver 36, when its enable terminal EN1 is at a high level, the PWM signal input to its input terminal S can pass through the first signal output terminal OUT1 to form a control signal (PWM-H) to drive the first driver 36. Two electronic switches Q2; on the other hand, when the enable terminal EN1 is at a low level, the control signal (PWM-H) is a turn off signal, so that the second electronic switch Q2 forms an open state. Similarly, in the second driver 37, when its enable terminal EN2 is at a high level, the PWM signal input to its input terminal S can pass through the second signal output terminal OUT2 to form a control signal (PWM-L) to The first electronic switch Q1 is driven; when the enable terminal EN2 is at a low level, the control signal (PWM-L) is a turn off signal, making the first electronic switch Q1 open.

The operation of the circuit is described below through the signal timing diagram shown in FIG. 3. For example, the voltage range received by the power input terminal 10 can be an extremely wide input voltage range of 9 volts to 160 volts, and 47 volts can be set as switching Therefore, the value of multiplying the resistance ratio of the voltage dividing circuit 33 by 47 can be used as the voltage of the voltage switching point setting terminal Vset. When the input voltage (+VIN) of the power input terminal 10 is lower than 47 volts, the voltage of the detection terminal DET of the comparator 34 is lower than the voltage of the voltage switching point setting terminal Vset, so the output terminal VC1 of the comparator 34 Output low level; at this time, the enable terminal EN1 of the first driver 36 receives the low level, so the control signal (PWM_H) output by the first signal output terminal OUT1 is the cut-off signal, so that the second electronic switch Q2 is opened; at the same time , the enable terminal EN2 of the second driver 37 receives a high potential through the inverter 35, so the control signal (PWM_L) output by the second signal output terminal OUT2 is a PWM signal for the first electronic switch Q1 to work . Therefore, the output winding Ns and the first winding Np1 conduct electromagnetic induction to generate a first inductive power supply, and the first inductive power supply is output to the next stage circuit or load through the output circuit 40 at the power output terminal 41 .

When the input voltage (+VIN) of the power input terminal 10 is higher than 47 volts, the voltage of the detection terminal DET of the comparator 34 is higher than the voltage of the voltage switching point setting terminal Vset, so the output terminal VC1 of the comparator 34 Output a high potential; at this time, the enable terminal EN1 of the first driver 36 receives a high potential, so the control signal (PWM_H) output by the first signal output terminal OUT1 is a PWM signal for the second electronic switch Q2 to work; The enable terminal EN2 of the second driver 37 receives a low level through the inverter 35 , so the control signal (PWM_L) output by the second signal output terminal OUT2 is a cut-off signal to open the first electronic switch Q1 . Therefore, the output winding Ns and the second winding Np2 conduct electromagnetic induction to generate a second inductive power supply, which is output to the next stage circuit or load through the output circuit 40 at the power output terminal 41 .

It can be seen from the foregoing that when the input voltage (+VIN) is lower than the switching voltage, the first electronic switch Q1 is driven by the control signal (PWM_L) and the second electronic switch Q2 is open, and the anti-backflow element D1 can interrupt the The voltage and current paths coupled from the second winding Np2, thereby preventing the current of the second winding NP2 from directly entering the first winding Np1 and the first electronic switch Q1 when the first electronic switch Q1 is turned on, causing abnormality; In the state where the input voltage (+VIN) is higher than the switching voltage, the second electronic switch Q2 is driven by the control signal (PWM_H) and the first electronic switch Q1 is open circuit, wherein, for the input side of the transformer T1, more A high input voltage (+VIN) means a lower input current, and when the lower input current passes through the backflow preventing element D1, the loss of the backflow preventing element D1 can be minimized. Furthermore, although the input side of the transformer T1 has two windings Np1 and Np2, the current detection circuit 50 is connected in series between the connection node 21 of the first electronic switch Q1 and the second electronic switch Q2 and the ground, so In the present invention, only one current detection circuit 50 can detect the current value of the first winding Np1 or the second winding Np2, thereby reducing the current detection cost to a minimum. On the other hand, suitable transistor elements can be selected for the first electronic switch Q1 and the second electronic switch Q2. For example, a low-voltage switching element can be selected for the first electronic switch Q1, and a high-voltage switching element can be selected for the second electronic switch Q2. , Q2 respectively operate in the voltage range that meets the specification to optimize the power conversion efficiency.

In the embodiment of the present invention, the first winding Np1 is compared with the second winding Np2, because the second winding Np2 corresponds to a higher input voltage (+VIN), and the first winding Np1 corresponds to a lower input voltage (+VIN). ), so the number of coils of the second winding Np2 is greater than the number of coils of the first winding Np1, and the number of coils of the first winding Np1 can be equal to the number of coils of the output winding Ns. For example, if the range of the input voltage (+VIN) is 9V to 160V, and the output voltage of the output circuit 40 is 5V, then Np1:Np2:Ns=2:8:2, but not limited to this .

To sum up, in the present invention, the comparison unit 31 compares whether the input voltage (+VIN) is greater than the switching voltage, and drives one of the first electronic switch Q1 and the second electronic switch Q2 according to the comparison result. When the first electronic switch Q1 is driven and the second electronic switch Q2 is open, no current flows through the second winding Np2, and the duty cycle of the transformer T1 is based on the first winding Np1 and the output On the other hand, when the second electronic switch Q2 is driven and the first electronic switch Q1 is open, no current flows through the first winding Np1, and the duty cycle of the transformer T1 ( duty cycle) is determined according to the turns ratio of the second winding Np2 and the output winding Ns. According to the single-stage double-cut circuit structure of the present invention, through the setting of the two windings Np1, Np2 and the two electronic switches Q1, Q2, the transformer T1 has two turns ratios to choose from. The first winding Np1 The turns ratio of the output winding Ns corresponds to a lower input voltage range (eg, a range of 9 volts to 47 volts), and the turns ratio of the second winding Np2 to the output winding Ns corresponds to a higher input voltage range (eg, 47 volts) range to 160 volts); overall, the lower input voltage range combined with the higher input voltage range forms a very wide input voltage range (for example, the range of 9 volts to 160 volts), so the present invention can operate in a very wide range Input voltage range, and can maintain ideal power conversion efficiency.

Claims (10)

1. a single-stage double-cut type wide input range power conversion circuit, is characterized in that, comprises: a power input terminal; a switching node, connected to the power input; A transformer has an input side and an output side, the input side includes a first winding and a second winding connected to the switching node, the output side includes an output winding, wherein the first winding and the turns ratio of the output winding is different from the turns ratio of the second winding to the output winding; a first electronic switch, connected in series with the first winding and having a control terminal; a second electronic switch, connected in series with the second winding and having a control terminal; A pulse width modulation circuit includes a comparison unit and a PWM controller. The comparison unit has a detection terminal, a voltage switching point setting terminal, a PWM input terminal, a first signal output terminal and a second signal output terminal The detection terminal is connected to the power input terminal, the first signal output terminal is connected to the control terminal of the second electronic switch, and the second signal output terminal is connected to the control terminal of the first electronic switch; A PWM output end of the PWM controller is connected to the PWM input end of the comparison unit; and An output circuit is connected to the output winding of the transformer and includes a power output terminal. 2 . The single-stage double-cut wide input range power conversion circuit according to claim 1 , wherein the switching node is directly connected to the power input terminal. 3 . 3. The single-stage double-cut wide input range power conversion circuit according to any one of claims 1 or 2, wherein the first winding is directly connected to the switching node, and the second winding is A counterflow element connects the switching node. 4. The single-stage double-cut type wide input range power conversion circuit according to any one of claims 1 or 2, wherein the comparison unit comprises: A comparator has a positive input terminal, a negative input terminal and an output terminal, a resistor is connected between the positive input terminal and the output terminal, the positive input terminal is the detection terminal, and the negative input terminal is the detection terminal. The terminal is the voltage switching point setting terminal; an inverter, the input end of the inverter is connected to the output end of the comparator; a first driver, which has an enable terminal, an input terminal and the first signal output terminal, and the enable terminal of the first driver is connected to the input terminal of the inverter; A second driver has an enable terminal, an input terminal and the second signal output terminal, the enable terminal of the second driver is connected to the output terminal of the inverter, and the input terminal of the second driver The input terminal of the first driver is connected, and the input terminal of the first driver or the second driver is used as the PWM input terminal. 5. The single-stage double-cut type wide input range power conversion circuit as claimed in claim 3, wherein the comparison unit comprises: A comparator has a positive input terminal, a negative input terminal and an output terminal, a resistor is connected between the positive input terminal and the output terminal, the positive input terminal is the detection terminal, and the negative input terminal is the detection terminal. The terminal is the voltage switching point setting terminal; an inverter, the input end of the inverter is connected to the output end of the comparator; a first driver, which has an enable terminal, an input terminal and the first signal output terminal, and the enable terminal of the first driver is connected to the input terminal of the inverter; A second driver has an enable terminal, an input terminal and the second signal output terminal, the enable terminal of the second driver is connected to the output terminal of the inverter, and the input terminal of the second driver The input terminal of the first driver is connected, and the input terminal of the first driver or the second driver is used as the PWM input terminal. 6 . The single-stage double-cut wide input range power conversion circuit according to claim 5 , wherein the anti-backflow element is a diode, the anode end of the diode is connected to the switching node, and the cathode end of the diode is connected to the switching node. 7 . The extremes are connected to the second winding. 7 . The single-stage double-cut wide input range power conversion circuit according to claim 1 , wherein the first electronic switch is connected to the second electronic switch to form a connection node, and the the connection node is connected to a current detection circuit; An input end of the PWM controller is connected to the current detection circuit. 8 . The single-stage double-cut wide input range power conversion circuit of claim 3 , wherein the first electronic switch is connected to the second electronic switch to form a connection node, and the connection node is connected to a Current detection circuit; An input end of the PWM controller is connected to the current detection circuit. 9 . The single-stage double-cut wide input range power conversion circuit of claim 4 , wherein the number of coils of the second winding is greater than the number of coils of the first winding. 10 . 10 . The single-stage double-cut wide input range power conversion circuit according to claim 5 , wherein the number of coils of the second winding is greater than the number of coils of the first winding. 11 .

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