TWM580684U - Load status detecting device - Google Patents

Abstract

The present invention is a load state detecting device comprising a detecting unit, a rectifying and filtering unit, an amplifying unit and a comparing unit. The detecting unit includes a current comparator, and the primary side is configured to receive a main current of the power supply device. And correspondingly outputting a sensing current on the secondary side, after the rectifier filtering unit and the amplifying unit are converted into a voltage, the comparing unit compares the voltage with a reference voltage, and the comparison result can determine the output of the power supply. Whether the load enters a light load state, and if so, the comparison unit will output a light load signal that can be used for other control applications, such as controlling the power supply device to reduce power consumption for a purpose.

Description

Load status detecting device

The present invention relates to a device for detecting a load state, in particular, a detecting device capable of determining that an output load enters a light load state.

Power supply devices such as power converters or power supplies are widely used, such as industrial devices, consumer electronics, medical facilities, etc. In recent years, with the demand for energy saving, the power supply device is also facing high energy. Design and development of conversion efficiency and low power consumption targets. For relatively small and low power power conversions, a better circuit design is needed to avoid additional power loss.

The operating state of the power supply device can be roughly divided into full load, light load, no load, etc., and different power consumption performances are required in different states. Therefore, relevant detection circuits are usually designed in the power supply device to judge the current Working status. For example, when the power supply unit operates from light load to no-load state, if part of the electronic components can be turned off, the power consumption of the overall device can be reduced.

The design of some power supply devices is generally based on the current sensing of the resistive element, and the operating state of the device is judged according to the current sensing result. However, sensing by the resistive component usually generates more power consumption, which is not conducive to realizing the green energy of the power supply device. Claim.

The main purpose of the present invention is to provide a load state detecting device for detecting whether the output load of the power supply device is in a light load state, and outputting a light load signal when it is judged to be in a light load state.

To achieve the foregoing objective, the present load state detecting device is applied to a power supply device for detecting an output load of the power device, and the load state detecting device includes:

a detecting unit includes a current comparator, the primary side of the current measuring device is configured to detect an input current, and correspondingly generate a sensing current on the secondary side;

a rectifying and filtering unit is connected to the detecting unit, and the rectifying and filtering unit generates a first voltage according to the sensing current;

An amplifying unit is connected to the rectifying and filtering unit to amplify the first voltage to generate a second voltage;

a comparison unit is connected to the amplification unit, the comparison unit compares the second voltage with a reference voltage, and determines whether to output a light load signal according to the result of the comparison, the light load signal is used to indicate that the output load is in a light load state .

The present invention detects the current in the power supply device by using a detecting unit composed of a current transformer, for example, detecting the main current of the power supply device, and the main current can be taken from the current of the primary side of the transformer of the power supply device, and converting the current on the primary side of the transformer into After the voltage is compared with the reference voltage, it is determined whether the output load of the power supply device is in a light load state. For light load, a light load signal is output for subsequent circuits, for example, to control the switch on the secondary side of the transformer to reduce the current consumption, and achieve the green energy requirement for reducing power consumption.

Referring to FIG. 1 , the present invention is a load state detecting apparatus 100 , which includes a detecting unit 10 , a rectifying and filtering unit 20 , an amplifying unit 30 , and a comparing unit 40 .

The detecting unit 10 has a current transformer (CT) 11 whose primary side receives an input current and the secondary side outputs an induced current according to the magnitude of the input current.

The rectifying and filtering unit 20 is connected to the output of the detecting unit 10, and generates a first voltage V ₁ according to the induced current output by the detecting unit 10. The rectifying and filtering unit 20 includes a rectifying diode D1, a first capacitor C1 and a first resistor R1. The anode of the rectifying diode D1 is connected to the output of the detecting unit 10, that is, the second of the current transformer 11 On the side, the induced current can pass through the rectifying diode D1. A cathode connected to the rectification diode D1 is connected in parallel to the first capacitor C1 and first resistor R1, the first capacitor C1 may provide a stabilizing effect on the first voltage V ₁ is, the first voltage V ₁ is rendered stable DC voltage To avoid the unstable state of the voltage. In this embodiment, the rectifying and filtering unit 20 further includes a second resistor R2 and a third resistor R3 connected between the anode of the rectifying diode D1 and the secondary side of the current transformer 11 . The third resistor R3 is connected across the secondary side of the flow comparator 11. The first voltage V _{1 is} output from the negative electrode of the rectifying diode D1.

The amplifying unit 30 is connected to the output of the rectifying and filtering unit 20 for amplifying the first voltage V ₁ to generate a second voltage V ₂ . The amplifying unit 30 is mainly composed of an operational amplifier 31. The non-inverting input terminal of the operational amplifier 31 is connected to the negative pole of the rectifying diode D1, and the second voltage V ₂ is output from the output terminal of the operational amplifier 31 to the next stage. Comparison unit 40. In order to reduce noise, a second capacitor C2 may be connected between the non-inverting input terminal and the ground, and a third capacitor C3 may be connected between the inverting input terminal and the output terminal of the operational amplifier 31.

The comparing unit 40 compares the second voltage V ₂ with a reference voltage V _ref to determine whether the output load is in a light load state. The comparison unit 40 has a comparator 41. The input terminal of the comparator 41 receives the second voltage V ₂ , and the other input terminal receives the reference voltage V _ref , which is required in the embodiment according to the design of the circuit. The negative input terminal of the device 41 receives the second voltage V ₂ , the positive input terminal of the comparator 41 receives the reference voltage V _ref , and when the second voltage V _{2 is} less than the reference voltage V _ref , the comparator 41 outputs a high level The light load signal indicates that the output load is light load. To improve the stability of the second voltage V ₂ and reduce noise, a fourth capacitor C4 may be disposed between the negative input terminal of the comparator 41 and the ground. Road noise. In other examples, the comparison of the second voltage V ₂ with the reference voltage V _ref may be changed according to the design requirements of the circuit, and the comparator 41 outputs a low-level light-load signal to indicate that the output load is in a light load state. The reference voltage V _ref can be provided by a voltage dividing circuit 42. The voltage dividing circuit is composed of a fourth resistor R4 and a fifth resistor R5 connected in series, and the voltage dividing circuit 42 is used to divide the working voltage VCC1 to obtain a voltage. the reference voltage V _ref, the reference voltage V _ref input to the positive input terminal of the comparator 41.

In the comparison unit 40, a hysteresis circuit is further provided, and the hysteresis circuit includes a diode D2, a sixth resistor R6, and a seventh resistor R7. The diode D2 and the sixth resistor R6 are connected in series between the output end of the comparator 41 and the positive input terminal. The seventh resistor R7 is connected across the positive input end of the comparator 41 and the voltage dividing node of the voltage dividing circuit 42. .

For a practical application of the present invention, the power supply device includes a transformer 210, a current detecting unit 220, a main controller 230, and an isolated driver 240. And a feedback unit 250.

The current detecting unit 220 is connected to the primary side (input side) of the transformer 210. The current detecting unit 220 can be a current transformer (CT) or a current sensing resistor on the secondary side of the transformer 210 (output side). Having a first switch QA and a second switch QB, connected to the output terminal +VO, -VO through the first switch QA and the second switch QB, the output terminal +VO, -VO for an output Load connection.

The main controller 230 generates a set of control signals according to a current sensing signal output by the current detecting unit 220 and a feedback signal FB output by the feedback unit 250, and uses the set of control signals to determine the primary side switch QC, QD switching action. The feedback unit 250 detects the state of the output terminals +VO, -VO and provides the feedback signal to the main controller 230.

The load state detecting device 100 of the present invention is connected in parallel to the current detecting unit 220, and extracts a part of the current passing through the primary side switch QD as the sensing current I ₁ , and determines the output load according to the sensing current I _{1 .} The working state, when it is determined to be a light load state, outputs a light load signal to the isolation driver 240, so that the isolation driver 240 turns off the first switching switch QA and the second switching switch QB on the secondary side. Since the load state detecting device 100 is connected in parallel with the current detecting unit 220 in the power supply device, the impedance can be reduced to reduce power consumption.

To facilitate the description of the circuit operation of the load state detecting device 100 in the power supply device, please refer to FIG. 3 further, and the waveforms represent the following meanings: I _o : output current I ₁ through the output load: sensing current V ₂ : The second voltage V _ref inside the load state detecting device 100 : the reference voltage E ₂ inside the load state detecting device 100 : the light load signal VOA outputted by the load state detecting device 100 : the first one of the first switching switch QA is controlled Control signal VOB: controlling the second control signal of the second switch QB

In the period T0 ~ T1, the state of full output load (full load), 100 because the second voltage V ₂ is greater than the reference voltage V _ref load state detection means, the signal output from the comparator 41 exhibits a low level, and therefore, The isolation driver 240 normally outputs the first control signal VOA and the second control signal VOB to control the first switching switch QA and the second switching switch QB to be respectively turned ON/OFF.

In the period T1 ~ T2, the output current I _o and I ₁ based sensing current gradually decreases, voltage V 100 is a second load condition detecting means ₂ also showed a decline in sync, the second voltage V ₂ has not been lower than the reference voltage V Before the _ref , the isolation driver 240 still outputs the first control signal VOA and the second control signal VOB normally, and controls the first switching switch QA and the second switching switch QB to be alternately turned on/off.

After the time point T2, the output current I _o and I ₁ sense current has decreased to some extent, the output load has entered the "light load" state, the load state detection means 100 at this time because the second voltage V ₂ is less than the reference voltage V _Ref , the comparator 41 outputs a high-level light load signal E ₂ to the isolation driver 240 , the isolation driver 240 stops outputting the first control signal VOA, the second control signal VOB, the first switching switch QA and the second switching switch QB Both are maintained. The secondary side rectification path of the transformer 210 is only passed through the body diodes of the first switching switch QA and the second switching switch QB to achieve light load energy saving effect.

Creation sensing field of application of the load state detection apparatus 100 is not limited to the power supply device in FIG. 2, other devices are also possible in which the load state detecting device 100 accessible as long as the sensing current I ₁ is an alternating current or pulsating DC, according to the sensing current I _{1 to} determine whether the output load is in a light load state. When it is judged to be in a light load state, a light load signal E ₂ is output for other circuit applications, for example, in the present embodiment, the light load signal E _{2 is} supplied to the isolation driver 240 to turn off the secondary side related component, but the light load signal E The use of ₂ is not limited to this.

Furthermore, the present invention uses the comparator 11 as the main component of the current sensing in the detecting unit 10. Compared with the sensing current using the resistive element, the present invention can reduce the power and simultaneously ensure the secondary of the current transformer 11. The side still provides a signal of sufficient strength to determine the light load condition.

100‧‧‧Load state detection device

10‧‧‧Detection unit  11‧‧‧ Current comparator

20‧‧‧Rectifier Filter Unit  30‧‧‧Amplification unit

31‧‧‧Operational Amplifier  40‧‧‧Comparative unit

41‧‧‧ Comparator  42‧‧‧voltage circuit

210‧‧‧Transformer  220‧‧‧current detection unit

230‧‧‧Master controller  240‧‧‧Isolated drive

250‧‧‧return unit  D1‧‧‧Rected Diode

C1~C4‧‧‧first capacitor~fourth capacitor  R1~R7‧‧‧First resistance~ seventh resistance

V ₁ ‧‧‧First voltage

V ₂ ‧‧‧second voltage

V _ref ‧‧‧reference voltage

QA‧‧‧First switch

QB‧‧‧Second switch

QC, QD‧‧‧ primary side switch

I _o ‧‧‧Output current

I ₁ ‧‧‧Sensing current

Figure 1: Detailed circuit diagram of the present load state detection device.  Figure 2: Detailed circuit diagram of the present load state detecting device applied to a power supply device.  Figure 3: Schematic diagram of the relevant waveforms of the circuit of Figure 2.  

Claims (10)

A load state detecting device is connected to a power supply device for detecting a state of an output load of one of the power supply devices, the load state detecting device comprising:  a detecting unit includes a current comparator, the primary side of the current measuring device is configured to detect an input current, and correspondingly generate a sensing current on the secondary side;  a rectifying and filtering unit is connected to the detecting unit, and the rectifying and filtering unit generates a first voltage according to the sensing current;  An amplifying unit is connected to the rectifying and filtering unit to amplify the first voltage to generate a second voltage;  a comparison unit, connected to the amplifying unit, the comparing unit compares the second voltage with a reference voltage to obtain a comparison result, and according to the comparison result, whether to output a light load signal, the light load signal is used to represent the output The load is in a light load state.   The load state detecting device of claim 1, wherein the rectifying and filtering unit comprises:  a rectifying diode, the anode of the rectifying diode being connected to the secondary side of the current transformer, allowing the sensing current to pass through the rectifying diode;  A first capacitor and a first resistor are connected in parallel with each other and connected between the cathode of the rectifier diode and the ground.   The load status detecting device of claim 2, wherein the amplifying unit comprises:  An operational amplifier having a non-inverting input coupled to a negative terminal of the rectifying diode, the operational amplifier amplifying the first voltage, and outputting the second voltage at an output of the operational amplifier.   The load status detecting device of claim 3, wherein the comparing unit comprises:  A comparator, an input terminal receives the reference voltage, and another input terminal receives the second voltage, and an output end of the comparator is configured to output the light load signal.   The load state detecting device of claim 4, wherein the positive input terminal of the comparator is connected to a voltage dividing circuit to receive the reference voltage generated by the voltage dividing circuit; the negative input terminal of the comparator An output of the operational amplifier is coupled to receive the second voltage. The load state detecting device of claim 5, wherein the rectifying and filtering unit comprises:  a second resistor connected in series between the anode of the rectifier diode and the secondary side of the current transformer;  A third resistor is connected across the secondary side of the current comparator.   The load status detecting device of claim 5, wherein the voltage dividing circuit comprises:  a fourth resistor and a fifth resistor are connected in series between an operating voltage and a ground, wherein the series connection of the fourth resistor and the fifth resistor is a voltage dividing node.   The load state detecting device of claim 7, wherein the comparing unit further comprises a hysteresis circuit, the hysteresis circuit comprising a diode, a sixth resistor and a seventh resistor;  The diode and the sixth resistor are connected in series, and then connected between the output end of the comparator and the positive input end of the comparator;  The seventh resistor is connected across the positive input of the comparator and the voltage dividing node of the voltage divider circuit.   The load state detecting device of claim 8, wherein a second capacitor is connected between the non-inverting input terminal of the operational amplifier and the ground; and the third capacitor is connected between the inverting input terminal and the output terminal of the operational amplifier. . The load state detecting device of claim 9, wherein the comparator outputs the light load signal of the high level when the second voltage is lower than the reference voltage.