Detection circuit

Abstract

The present invention provides a detection circuit for the working state of a converter that can be applied to various topological structures, comprising: a first input terminal, connected to the secondary coil of the converter; a first rectifying element, the anode of which is connected to the first input terminal; a first resistor, which is connected in series with the first rectifying element; a first capacitor, which is connected to the first resistor; a first output terminal, which is connected to the connection point between the first resistor and the first capacitor, and outputs a first potential as a power supply voltage for a specific functional unit; a ground terminal, which is connected to the first capacitor; and a circuit unit, which is connected between the first rectifying element and the first resistor, the circuit unit comprising: a first switching element, whose first end is connected to the first resistor and whose third end is connected to the first rectifying element; a second rectifying element, which is connected between the second end and the first end of the first switching element; and a second capacitor, which is connected between the second end and the first input terminal of the first switching element, a voltage divider circuit is connected between the first output terminal and the ground terminal, and a voltage divider point of the voltage divider circuit is connected to a control signal via the second switching element.

Description

Technical Field

[0001] The invention relates to a detection circuit for the working state of a converter. Background Art

[0002] In order to ensure the correct operation of the converter and its ability to cope with a variety of complex application conditions, a detection circuit for the converter's working status is usually required inside the converter. The detection circuit needs to have a certain load capacity and low-delay response characteristics. Figure 4 The rectifier scheme B21 (diode common cathode mode), the existing detection circuit 40 for the converter is one of the simple methods, such as Figure 4 As shown, the converter 102 has a primary coil T101-P and a secondary coil T101-S. The secondary coil T101-S is connected to two diodes D1a and D1b configured in a common cathode mode. The voltage rectified by the diodes D1a and D1b is transmitted through the inductor Lr and the capacitor C O The filter circuit is formed and output to the output terminal Vout. The detection circuit 40 comprises: a diode D100 and a resistor R100 connected in series, one end of the diode D100 is connected to the secondary coil of the converter 120; and a capacitor C100 connected to the resistor R100. The connection point between the resistor R100 and the capacitor C100 outputs a first potential as the power supply voltage Vcc of the specific functional unit, and the resistor R1 and the resistor R2 form a voltage divider circuit as an indication signal of the working state. The voltage divider point of the voltage divider circuit is connected to the transistor, the base of which is connected to the connection point between the resistor R1 and the resistor R2, the emitter is connected to the other end of the resistor R2, and the collector is connected to the control signal.

[0003] The first output voltage Vcc can be used as the working voltage of the relevant functional circuits, such as the power supply voltage of the output low voltage protection circuit LVP (Low Vout Voltage Protection). The LVP circuit detects the output voltage. When Vo is less than the set voltage, the circuit will output a protection shutdown signal after the set delay time. After the protection shutdown signal is output, the power supply stops working, and the LVP circuit needs to be automatically reset, that is, the voltage of the capacitor C100 needs to be automatically reset to zero.

[0004] The control signal can be used for: detecting the working status of the converter, PC bus switching, and Vout forced start loop.

[0005] However, the above detection circuit for the converter has the following disadvantages:

[0006] 1. As the input voltage and output load change, the voltage at point Pout changes greatly (Vpout≈kVin);

[0007] 2. When a high value capacitor C100 is set, the control signal will have a larger delay time. However, when the capacitance of C100 is too small, the LVP circuit will not have enough energy, so that the LVP line cannot work normally, and the control signal will become unstable under light load or no load conditions.

[0008] 3. For the OCP (over current protection) hiccup mode, in the fault mode of no-load short circuit or short circuit start, due to insufficient voltage of C100, the LVP circuit cannot work normally, resulting in the failure of the over current hiccup mode.

[0009] 4. The input voltage of the detection circuit is not suitable for topologies where energy can be obtained from the bus voltage of the parallel system.

[0010] In addition, the detection circuit 100 for the converter as described above cannot be applied to Figure 5 The rectification method B22 (diode common anode mode) shown and Figure 4 In the converter in which D1a is changed to MOSFET, for a single converter, if the output load is a battery or a large capacitive load, or for the outputs of multiple converters in parallel, if the output end of each converter is not connected to a redundant backup diode, when the converter itself fails and shuts down, the output bus voltage will become the source voltage of the fault power supply detection circuit, causing the detection circuit 100 to mistakenly believe that it is working normally. This design will not be able to identify its fault, and the related functional circuits will fail to output the correct fault command, causing the entire system to work abnormally. Summary of the invention

[0011] The present invention is accomplished in view of the above problems, and its object is to provide an improved detection circuit for the working state of a converter.

[0012] The detection circuit for the working state of the converter of the present invention is characterized by comprising: a first input terminal, which is connected to the secondary coil of the converter; a first rectifying element, whose anode is connected to the first input terminal; a first resistor, which is connected in series with the first rectifying element; a first capacitor, which is connected to the first resistor; a first output terminal, which is connected to the connection point between the first resistor and the first capacitor, and outputs a first potential as a power supply voltage for a specific functional unit; a ground terminal, which is connected to the first capacitor; and a first circuit unit, which is connected between the first rectifying element and the first resistor, and the first circuit unit includes: a first switching element, whose first end is connected to the first resistor and whose third end is connected to the first rectifying element; a second rectifying element, which is connected between the second end and the first end of the first switching element; and a second capacitor, which is connected between the second end of the first switching element and the first input terminal, and a voltage divider circuit is connected between the first output terminal and the ground terminal, and the voltage divider point of the voltage divider circuit is connected to a control signal via the second switching element.

[0013] In addition, another object of the present invention is to provide a low-delay detection circuit for the working state of a converter, comprising: a first input terminal, which is connected to the secondary coil of the converter; a first rectifying element, whose anode is connected to the first input terminal; a first resistor, which is connected in series with the first rectifying element; a first capacitor, which is connected to the first resistor; a first output terminal, which is connected to the connection point between the first resistor and the first capacitor, and outputs a first potential as a power supply voltage for a specific functional unit; a ground terminal, which is connected to the first capacitor; and a first circuit unit, which is connected between the first rectifying element and the first resistor, and the first circuit unit includes: a first switching element, whose first end is connected to the first resistor and the third end is connected to the first rectifying element; a second rectifying element, which is connected between the second end and the first end of the first switching element; and a second capacitor connected between the second end of the first switching element and the first input end, the detection circuit also has: a second circuit unit and a second output end, the second circuit unit includes: a fourth capacitor connected to the first input end; a fourth rectifier element, a cathode of which is connected to the fourth capacitor and an anode of which is connected to the ground end; a second resistor, one end of which is connected to the connection point between the fourth capacitor and the fourth rectifier element, and the other end is connected to the second output end; and a fifth capacitor and a third resistor connected in parallel between the other end of the second resistor and the ground end, a voltage divider circuit is connected between the second output end and the ground end, and the voltage divider point of the voltage divider circuit is connected to the control signal via the second switching element.

[0014] In addition, in the detection circuit of the present invention, a third capacitor or a third rectifying element is connected in parallel between the first end and the third end of the first switch element (the third capacitor and the third rectifying element are selected from the two).

[0015] In addition, in the detection circuit 20 of the present invention, the anode of the first rectifying element is not connected to the first input terminal but is connected to the auxiliary power supply of the converter.

[0016] Effects of the Invention

[0017] The detection circuit for a converter according to the present invention can be applied to various converter topologies;

[0018] Through energy feedback, the fluctuation amplitude of the output potential of the detection circuit can be significantly reduced, making the design of subsequent control loops more convenient;

[0019] At the same time, due to the feedback of energy, the loss can be reduced and the efficiency can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 1 is a circuit diagram of a detection circuit 10 for a converter according to a first embodiment of the present invention.

[0021] Figure 2 FIG. 2 is a circuit diagram of a detection circuit 20 for a converter according to a second embodiment of the present invention.

[0022] Figure 3 FIG. 2 is a circuit diagram of a detection circuit 30 for an inverter according to a third embodiment of the present invention.

[0023] Figure 4 FIG. 4 is a circuit diagram of a detection circuit 40 for a converter according to the prior art.

[0024] Figure 5 For illustration Figure 4 The detection circuit 40 shown is not suitable for the topology of the diode common anode mode. DETAILED DESCRIPTION

[0025] The present invention will be described in more detail below with reference to the accompanying drawings and embodiments.

[0026] Hereinafter, preferred embodiments of the power supply circuit according to the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same or corresponding parts are given the same reference numerals, and repeated descriptions are omitted.

[0027] (First Embodiment)

[0028] Figure 1 FIG. 1 is a circuit diagram of a detection circuit 10 for a converter according to a first embodiment of the present invention. Figure 4The structures shown are exactly the same and will not be described again here. Figure 1 As shown, the detection circuit 10 of the first embodiment comprises: a diode D100 and a resistor R100 connected in series, one end (anode) of the diode D100 is connected to the secondary coil 120 of the converter (i.e., the first input terminal Pin); a capacitor C100 connected to the resistor R100. The voltage Vpout of C100 serves as the power supply of the back-end signal control loop B2 and the input signal indicating the working state of the converter (Vpout high level: the converter is in normal working state, Vpout zero level: the converter stops working). The resistor R1 and the resistor R2 constitute a voltage divider circuit, the voltage divider point of the voltage divider circuit is connected to the transistor, the base of which is connected to the connection point between the resistor R1 and the resistor R2, the emitter is connected to the other end of the resistor R2, and the collector is connected to the control signal. Of course, B2 can also be other equivalent control loops.

[0029] In addition, a circuit unit 200 is inserted between the series-connected diode D100 and the resistor R100, which is one of the key loops of the present invention. The circuit unit 200 comprises: a switching element Q200, whose emitter is connected to the resistor R100 and the collector is connected to the diode D100. A diode D200 is connected between the base and emitter of the switching element Q200, and the diode can also be a voltage-stabilizing diode. The anode of the diode D200 is connected to the emitter of the switching element Q200, and the cathode of the diode D200 is connected to the base of the switching element Q200. In addition, the capacitor C200 is connected between the base of the switching element Q200 and the anode of the diode D100. Here, the switching element Q200 is described by taking an NPN bipolar transistor as an example, but as long as it can form the same circuit function, it is not limited to an NPN bipolar transistor, for example, it can be an N-channel field effect transistor, etc.

[0030] In addition, a capacitor C201 or a diode D201 (either one) is connected in parallel between the emitter and collector of the circuit unit 200 to prevent the collector and emitter of Q200 from being subjected to an excessive reverse voltage, which may damage Q200. However, the capacitor C201 and the diode D201 are not necessary components and may be removed according to circumstances, such as when Q200 is an N-channel field effect transistor.

[0031] Next, the operation of the detection circuit 10 for the converter will be described.

[0032] When the converter is working, the transformer secondary winding of the converter outputs a voltage pulse. When the positive pulse voltage is applied to capacitors C200 and D100 (ON time), due to the existence of C200, after the pulse voltage is applied, a pulse current will flow into the base of Q200 through capacitor C200, turning on the switch element Q200. The current path is as follows:

[0033] Path 1: Pin->C200->BE of Q200->R100->C100 and equivalent input impedance of B2 at the rear end->Pg (ground terminal)

[0034] Path 2: Pin->D100->CE of Q200->R100->C100 and equivalent input impedance of back-end B2->Pg (ground terminal)

[0035] When a negative pulse or zero voltage is applied to capacitors C200 and D100 (OFF time), the switching element Q200 is turned off. Its current path is as follows:

[0036] In such Figure 5 In the topology shown (diode common anode mode), C100->R100->D200->C200->Pin->Vout (output power supply)->Pg (ground terminal), during the OFF time, the energy of C200 and C100 returns to the power supply.

[0037] In such Figure 4 In the topology shown (diode common cathode mode), C100->R100->D200->C200->Pin->transformer secondary winding T101-S->Pg (ground terminal). During the OFF time, part of the energy is consumed in the resistor R100.

[0038] As a result, due to the energy feedback, the variation range of the voltage Vpout on C100 is significantly improved compared with the detection circuit 40 for the converter in the prior art. Figure 5 The diode common anode mode topology shown can reduce losses and thus further improve the efficiency of the power supply. The following are the measured values ​​of Vpout for a specific parameter at different input voltages:

[0039]

[0040] From the above data, it can be seen that when the input changes by nearly 4 times, the voltage of C100 of the detection circuit 10 of the present invention remains basically stable, and its voltage can be approximately expressed as V C100(10) ≈k*Vo (Vo is the output voltage of the converter), while the existing detection circuit 40 has a large change, and its voltage can be approximately expressed as V C100(40) ≈k*Vin (Vin is the input voltage of the converter).

[0041] Capacitor C200 is a DC blocking capacitor. Only pulse voltage can pass through the capacitor and then turn on Q200. Therefore, when the converter stops working, the Pin terminal will present a non-pulse voltage (zero level or DC voltage provided from the output bus). At this time, the Pin terminal level will be isolated by C200, so that the control circuit can provide a correct judgment signal. Diode D200 clamps the EB voltage of Q200 during the OFF time to protect Q200 and provide a path for energy feedback. Capacitor C201, diode D201 is optional and is used to clamp the EC voltage of Q200 during the OFF time to protect Q200.

[0042] According to the detection circuit 10 for a converter of the first embodiment, the following effects can be achieved:

[0043] 1. Compared with the detection circuit 40 of the related art, the detection circuit 10 used in the first embodiment can be applied to various topologies.

[0044] 2. Due to energy feedback, the variation range of the voltage Vpout on C100 is significantly improved compared with the detection circuit 40 for the converter in the prior art. In addition, Figure 5 The diode common anode mode topology shown can reduce losses and further improve the efficiency of the power supply.

[0045] (Second Embodiment)

[0046] Figure 2 2 is a circuit diagram of a detection circuit 20 for a converter according to a second embodiment of the present invention. The detection circuit 20 for a converter according to the second embodiment differs from the detection circuit 10 according to the first embodiment in that a diode D100 is connected to an auxiliary power supply (Aux) of the converter.

[0047] More specifically, the capacitor C200 is connected to the secondary coil of the converter 120 , and the anode of the diode D100 is not connected to the secondary coil of the converter 120 but is connected to the auxiliary power source Aux.

[0048] Next, the operation of the detection circuit 20 for the converter will be described.

[0049] When a positive pulse voltage is applied to capacitors C200 and D100 (ON time), the switch element Q200 is turned on. Its current path is as follows:

[0050] Path 1: Pin->C200->BE of Q200->R100->C100->Pg (ground terminal) Path 2: Aux->D100->CE of Q200->R100->C100->Pg (ground terminal)

[0051] For path 2, when the converter output load is no-load (or light load) or the output terminal is in a short-circuit state, under this load condition, the Pin terminal can only maintain a narrow pulse of a low level. For the detection circuit 10 of the first embodiment, the voltage on C100 can only maintain a relatively low level, which is insufficient to maintain the correct operation of the subsequent control loop (such as the LVP loop). Under other load conditions, the voltage on capacitor C100 is usually higher than the Aux potential, and path 2 is in a cut-off state.

[0052] When a negative pulse or zero voltage is applied to capacitor C200 (OFF time), switch element Q200 is turned off. Its current path is the same as that of the first embodiment and will not be described in detail here.

[0053] According to the detection circuit 20 of the second embodiment, it can achieve the same technical effect as the detection circuit 10 of the first embodiment. In addition, since the diode D100 is connected to the fixed auxiliary power supply Aux, C100 can maintain sufficient voltage in any circuit state (for example, no load, no load (or light load) or short circuit condition) to maintain the correct operation of the subsequent control loop.

[0054] (Third Embodiment)

[0055] Figure 3 2 is a circuit diagram of a detection circuit 30 for a converter according to a third embodiment of the present invention. The detection circuit 30 for a converter according to the third embodiment differs from the detection circuit 20 for a converter according to the second embodiment in that a circuit unit 300 is added.

[0056] The circuit unit 200 of the detection circuit 30 of the third embodiment is completely the same as the detection circuit 20 of the second embodiment, and will not be described again.

[0057] The circuit unit 300 comprises: a capacitor C300 connected to the secondary coil of the converter 120; a diode D300 having a cathode connected to the capacitor C300 and an anode connected to the ground; a resistor R300 having one end connected to a connection point between the capacitor C300 and the diode D300 and the other end connected to a voltage-dividing resistor R1 of a voltage-dividing circuit; and a capacitor C301 and a resistor R301 connected in parallel between the voltage-dividing resistor R1 of the voltage-dividing circuit and the ground.

[0058] Next, the operation of the detection circuit 30 for the converter will be described.

[0059] When a positive pulse voltage is applied to capacitor C300 (ON time), capacitor C301 is charged. In order to achieve a fast response, the capacitance value of capacitor C301 is much smaller than that of capacitor C100. Its current path is as follows:

[0060] Pin->C300->R300->C301 / / R301 and back-end B2 equivalent input impedance->Pg (ground terminal)

[0061] Diode D300 clamps the voltage of resistor R300 and provides a freewheeling path for C300 during the negative voltage or zero voltage duration (OFF time) of the pulse. The current path is as follows:

[0062] D300->C300->Pin->Vout (power supply output)->Pg (ground terminal)

[0063] C301->R300->C300->Pin->Vout->Pg (ground terminal)

[0064] During the OFF time, the energy of capacitors C300 and C301 returns to the power supply. The main purpose of introducing the circuit unit 300 is to provide a detection circuit with a faster response speed and applicable to various topologies. Therefore, the values ​​of capacitors C300 and C301 are smaller than C100 in the circuit 200, and the loss and return energy of the circuit itself are both smaller.

[0065] As a result, the circuit unit 300 has a faster response speed. In addition, the variation range of the voltage Vpout on C301 is significantly improved compared with the detection circuit 40 for the converter in the prior art. The following are the measured values ​​of Vpout of a specific parameter at different input voltages:

[0066]

[0067] From the above data, it can be seen that when the input changes by nearly 4 times, the voltage of the capacitor C301 of the detection circuit 30 of the present invention remains basically stable, and its voltage can be approximately expressed as V C301(30) ≈k*Vo (Vo is the output voltage of the converter), while the existing detection circuit 40 has a large change, and its voltage can be approximately expressed as V C100(40) ≈k*Vin (Vin is the input voltage of the converter).

[0068] According to the detection circuit 30 of the third embodiment, it can achieve the same technical effect as the detection circuit 20 of the second embodiment. In addition, the circuit unit 300 has a faster response speed and can handle control signals with a fast response requirement.

[0069] Furthermore, the circuit unit 300 in the third embodiment can also be applied to the detection circuit 10 in the first embodiment, and similar effects can be obtained.

[0070] Although the present invention is specifically described above in conjunction with the accompanying drawings and embodiments, it is to be understood that the above description does not limit the present invention in any form. Those skilled in the art can deform and change the present invention as needed without departing from the essential spirit and scope of the present invention, and each implementation unit can be used independently or in combination, and these deformations, changes and independent or combined use all fall within the scope of the present invention.

Claims

1. A detection circuit for the working state of a converter, It is characterized in that have: A first input terminal connected to the secondary coil of the converter; A first rectifying element, an anode of which is connected to the first input terminal; a first resistor connected in series with the first rectifying element; A first capacitor, one end of which is connected to the first resistor; a first output terminal, connected to a connection point between the first resistor and the first capacitor, outputting a first potential as a supply voltage of a back-end signal control loop, the first potential being used to indicate a working state of the converter; A ground terminal connected to the other end of the first capacitor; as well as A first circuit unit is connected between the first rectifying element and the first resistor, The first circuit unit comprises: a first switch element, a first end of which is connected to the first resistor, and a third end of which is connected to the first rectifying element; A second rectifying element connected between the second end and the first end of the first switching element; and a second capacitor connected between the second end of the first switch element and the first input end, A voltage divider circuit is connected between the first output terminal and the ground terminal, and a voltage dividing point of the voltage divider circuit is connected to a control signal via a second switch element.

2. The detection circuit according to claim 1, It is characterized in that A third capacitor or a third rectifying element is also connected in parallel between the first end and the third end of the first switch element.

3. The detection circuit according to claim 1 or 2, It is characterized in that An anode of the first rectifying element is not connected to the first input terminal but is connected to an auxiliary power supply.

4. A detection circuit for the working state of a converter, It is characterized in that have: A first input terminal connected to the secondary coil of the converter; A first rectifying element, an anode of which is connected to the first input terminal; a first resistor connected in series with the first rectifying element; A first capacitor, one end of which is connected to the first resistor; a first output terminal, connected to a connection point between the first resistor and the first capacitor, outputting a first potential as a supply voltage of a back-end signal control loop, the first potential being used to indicate a working state of the converter; A ground terminal connected to the other end of the first capacitor; as well as A first circuit unit is connected between the first rectifying element and the first resistor, The first circuit unit comprises: a first switch element, a first end of which is connected to the first resistor, and a third end of which is connected to the first rectifying element; A second rectifying element connected between the second end and the first end of the first switching element; and a second capacitor connected between the second end of the first switch element and the first input end, The detection circuit further comprises: a second circuit unit and a second output terminal, The second circuit unit comprises: a fourth capacitor connected to the first input terminal; a fourth rectifying element, whose cathode is connected to the fourth capacitor and whose anode is connected to the ground terminal; a second resistor, one end of which is connected to the connection point between the fourth capacitor and the fourth rectifying element, and the other end of which is connected to the second output terminal; and a fifth capacitor and a third resistor connected in parallel between the other end of the second resistor and the ground terminal, A voltage divider circuit is connected between the second output terminal and the ground terminal, and a voltage dividing point of the voltage divider circuit is connected to a control signal via a second switch element.

5. The detection circuit as claimed in claim 4, It is characterized in that A third capacitor or a third rectifying element is also connected in parallel between the first end and the third end of the first switch element.

6. The detection circuit according to claim 4 or 5, It is characterized in that An anode of the first rectifying element is not connected to the first input terminal but is connected to an auxiliary power supply.

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