Power failure detection and boost conversion circuit and device

Abstract

The utility model relates to the technical field of power line carrier communication, in particular to a power failure detection and boost conversion circuit and device. The power failure detection and boost circuit comprises at least one DC-DC boost converter, a capacitor C1 and a power failure detection and boost circuit based on a Zener diode. The capacitor C1 is connected into the circuit to provide stored energy of a power supply VCC for power failure detection; and the effective time of the EN high level and the working voltage IN is prolonged. The capacitor C1 is connected into the circuit to form an R / C time delay circuit or a D / C time delay circuit. According to the utility model, the capacitor is added to supplement energy storage for the power supply of the power failure detection circuit, the resistor or the diode is added to reduce reverse discharge, and the effective duration of DC-DC boost enabling and PWM working voltage is prolonged; after the power supply is powered off, the retention time of power-down detection output high level is prolonged, the retention time of PWM working voltage of the DC-DC boost converter is prolonged, and it is ensured that DC-DC boost conversion succeeds under the limiting condition.

Description

TECHNICAL FIELD

[0001] The utility model relates to power line carrier communication technical field, especially a power supply power failure detection and boost conversion circuit. BACKGROUND

[0002] In order to be able to carry out real-time meter reading measurement to terminal power consumption, the power department installs a meter reading communication module in the intelligent electric meter, can carry out data exchange through self-organizing network under the dispatching of system, and real-time uploads the electric meter power consumption data.

[0003] There is a special situation, when the power grid suddenly power failure, the communication module needs emergency processing, timely uploads the electric meter collected power consumption data. Generally, the communication module has no backup power supply, relies on super capacitor energy storage to provide emergency power supply for the whole module, and the standard requires that the super capacitor should provide at least 60 seconds of power for the data transmission of the communication module.

[0004] When the power grid power failure, the communication module must accurately perceive power failure, and should detect the power failure starting time as soon as possible, inform the MCU to enter the emergency processing flow, and quickly start the super capacitor DC-DC boost to supplement the total power supply. From the power grid power failure time, to the super capacitor starts to supply power to the circuit, there is ms level conversion transition time between the two, and in this transition time, the electric quantity stored in the large filter capacitor on each power supply temporarily provides energy for the normal work of the circuit.

[0005] Despite this, the electric quantity stored in the large filter capacitor on the power supply is extremely limited, and can only maintain the normal work of the circuit for less than 2ms, from power failure detection to super capacitor DC-DC boost output must be completed in this time.

[0006] In the prior art, there are two technical means for power failure detection: using a comparator or using a zener diode. The comparator generally adopts a hysteresis circuit structure, as shown in Figure 1 The comparison threshold of the power failure process is lower than that of the power-on process, and the comparison threshold of the power-on process is slightly higher; the zener diode has a conduction transition voltage, and the transition voltages of the power failure process and the power-on process are equal. See Figure 2 The role of the triode Q1 is polarity conversion, and the boost enable EN of the super capacitor is high level.

[0007] DC-DC boost converter has two types: high level enable and low level enable. Most DC-DC boost converter enable adopts high level effective, if DC-DC boost converter with high level enable, a problem may be encountered: in the power down process, the working power supply voltage is constantly decreasing, the high level voltage of the enable end EN is also constantly decreasing, because the DC-DC boost converter has a start delay, if the voltage of the enable end EN has decreased below the minimum effective voltage value before the start delay ends, or the working voltage of the DC-DC boost converter decreases below the minimum threshold voltage, then the DC-DC boost conversion will fail, so that the module cannot continue to work.

[0008] Because the device parameters have discreteness, the voltage turning point of the zener diode, the soft start delay of the DC-DC boost converter, the circuit load current, the capacitance value of the power filter capacitor, etc. all have differences, if the comprehensive effect of these differences exceeds a certain range, DC-DC boost conversion failure may be caused. Based on this, a power down detection and boost conversion device is proposed. Practical new type content

[0009] The utility model aims at the problems in the prior art, and provides a power down detection and boost conversion device; the utility model; after power down, the maintaining time of the high level of the power down detection output is prolonged, the maintaining time of the PWM working voltage of the DC-DC boost converter is prolonged, and DC-DC boost conversion is ensured to be successful under the limit condition. The circuit is simple, and the cost is low.

[0010] The technical scheme of the utility model;

[0011] The utility model discloses a power down detection and boost conversion circuit, which comprises at least one DC-DC boost converter, a capacitor C1 and a power down detection and boost circuit based on a zener diode and a super capacitor.

[0012] The capacitor C1 is connected in the circuit to provide energy storage for power down detection of the power supply VCC; the effective time of the EN high level and the working voltage IN is prolonged.

[0013] The capacitor C1 is connected in the circuit to provide energy storage for power down detection of the power supply VCC; the effective time of the EN high level and the working voltage IN is prolonged.

[0014] Preferably, one end of the resistor R1 in the R / C delay circuit is grounded, and the other end is connected in series with the anode of the zener diode D2.

[0015] The cathode of the zener diode D2 is connected with the anode of the zener diode D1, and the cathode of the zener diode D1 is connected with Vout.

[0016] The power supply Vcc is connected in series with the resistor R4 and one end of the capacitor C1, and the other end of the capacitor C1 is grounded.

[0017] The input end of the DC-DC converter is connected with the output end of the resistor R4, and the output end of the DC-DC converter is connected with Vout; the output power of the DC-DC converter comes from a separate super capacitor;

[0018] The first end of the collector of the triode Q1 is connected with the output end of the resistor R4 after being connected with the resistor R3 in series, and the second end is connected with the enable end of the DC-DC conversion chip and the MCU INT; the base of the triode Q1 is connected with the anode of the Zener diode D2 after being connected with the resistor R2 in series; and the emitter of the triode Q1 is grounded.

[0019] The capacitor C1 is added to provide power VCC energy storage for power failure detection, and the resistor R4 is connected in series to limit the discharge current and prolong the effective time of the EN high level and the working voltage IN.

[0020] Before the system power failure, the output EN of the collector of the triode Q1 is low; in a short time after the power failure, the EN is pulled up by VCC; with the passage of time, the voltage of the main power supply VCC rapidly decreases, and the voltage of the EN and IN also decreases; the added resistor R4 and capacitor C1 provide energy storage delay, and if the discharge time constant is When the voltage across C1 decreases to 70% of the initial value, the time will be at least extended .

[0021] Preferably, one end of the resistor R1 in the D / C delay circuit is grounded, and the other end is connected with the anode of the Zener diode D2 in series;

[0022] The cathode of the Zener diode D2 is connected with Vin and the anode of the Zener diode D1; the cathode of the Zener diode D1 is connected with Vout;

[0023] The anode of the diode D3 and one end of the capacitor C1 are connected with the power supply Vcc in series, and the other end of the capacitor C1 is grounded;

[0024] The input end of the DC-DC conversion chip is connected with the cathode of the diode D3, and the output end of the DC-DC conversion chip is connected with Vout; the output power of the DC-DC converter comes from a separate super capacitor;

[0025] The first end of the collector of the triode Q1 is connected with the cathode of the diode D3 after being connected with the resistor R3 in series, and the second end is connected with the enable end of the DC-DC conversion chip and the MCU INT; the base of the triode Q1 is connected with the anode of the Zener diode D2 after being connected with the resistor R2 in series; and the emitter of the triode Q1 is grounded.

[0026] The capacitor C1 is added to provide power VCC energy storage for power failure detection, and the diode D3 is connected in series to isolate the reverse discharge current, so that the holding time of the EN high level and the working voltage IN is prolonged more.

[0027] By using the unidirectional conductivity of the diode, after the power supply is powered off, VCC rapidly decreases, the voltage across the capacitor C1 is higher than the VCC side, and the diode D3 is cut off; since the transistor Q1 is almost cut off, the discharge current of the capacitor C1 is very small, so that the discharge time of the capacitor C1 is greatly prolonged; when the impedance of the parallel connection of the collector of the transistor Q1, the EN end and the MCU INT end is Rin, and the equivalent load resistance of the IN end of the DC-DC boost converter is RL, then the time constant is ;

[0028] Under the condition that the PWM working voltage IN of the DC-DC boost converter is high enough, after the EN high level is effective, the DC-DC boost converter enters soft start, and delays After the delay, if the voltage of the EN end is still higher than the minimum effective voltage value, the DC-DC boost converter successfully boosts the output, the electrical energy stored in the super capacitor is converted through the boost conversion, the working power supply of the circuit is supplemented, and the working time of the communication module is prolonged.

[0029] The second aspect of the utility model provides a kind of application of power supply power failure detection and boost conversion circuit, use the power supply power failure detection and boost conversion circuit described above is applied in intelligent electric meter communication module, from the moment of power failure of power grid, to super capacitor starts to supply power to circuit, between the two, the electrical quantity stored in the large filter capacitor on each working power supply temporarily provides the energy of normal operation for circuit.

[0030] The third aspect of the utility model provides a kind of power supply power failure detection and boost conversion device, including the power supply power failure detection and boost conversion circuit described above, and carries out power supply power failure detection and boost conversion.

[0031] Compared with prior art, the utility model has the following beneficial technical effects:

[0032] The utility model adds a capacitor to supplement the energy storage of power supply detection circuit, adds a resistance or diode to reduce reverse discharge, prolongs the effective duration of DC-DC boost enable and PWM working voltage; after power supply is powered off, the holding time of power failure detection output high level is prolonged, the holding time of DC-DC boost converter PWM working voltage is prolonged, and DC-DC boost conversion is ensured to be successful in limit condition. The low cost is used to solve the small probability event that DC-DC boost conversion fails after power supply is powered off. ACCURACY OF DRAWINGS

[0033] Figure 1 It is a comparator power failure detection and boost circuit diagram in prior art;

[0034] Figure 2 It is a zener diode power failure detection and boost circuit diagram in prior art;

[0035] Figure 3 Circuit diagram of the improved R / C delay implementation scheme of the embodiment of the utility model;

[0036] Figure 4 Circuit diagram of the improved D / C delay implementation scheme of the embodiment of the utility model;

[0037] Figure 5 Circuit diagram of the embodiment 1 of the embodiment of the utility model. DETAILED DESCRIPTION Embodiment 1

[0038] The utility model provides a kind of power supply power failure detection and boost conversion circuit, comprising: at least one DC-DC boost converter, a capacitor C1 and the power failure detection based on zener diode, boost circuit and super capacitor;

[0039] The capacitor C1 is accessed in circuit to provide energy storage for power supply VCC of power failure detection;The effective time of extension EN high level and operating voltage IN.

[0040] The capacitor C1 is accessed in circuit to constitute R / C delay circuit or D / C delay circuit.

[0041] In an alternative embodiment, as shown in Figure 3 The anode of zener diode D2 is connected to ground at one end of resistance R1 in R / C delay circuit, and is connected in series at the other end;The cathode of zener diode D2 is connected to Vin and the anode of zener diode D1;The cathode of zener diode D1 is connected to Vout;Power supply Vcc is connected in series with resistance R4 and one end of capacitor C1, and the other end of C1 is connected to ground;The output end of resistance R4 is connected to the input end of DC-DC conversion chip, and the output end of DC-DC conversion chip is connected to Vout;The output electric energy of DC-DC boost converter comes from separate super capacitor;The first end of collector of triode Q1 is connected to the output end of resistance R4 after being connected in series with resistance R3, and the second end is connected to the enable end of DC-DC conversion chip and MCU INT;The base of triode Q1 is connected to the anode of zener diode D2 after being connected in series with resistance R2;The emitter of triode Q1 is connected to ground.Add capacitor C1 to provide power supply VCC energy storage for power failure detection, and connect resistance R4 in series to limit discharge current, to extend the effective time of EN high level and operating voltage IN.

[0042] Before system power failure, the output EN of collector of triode Q1 is low level;In a short time after power failure, EN is pulled up by VCC;With time going by, the voltage of main power supply VCC drops rapidly, and the voltage of EN and IN also drops;Increased resistance R4 and capacitor C1 provide energy storage delay, and if discharge time constant is τ1, the time of the voltage at both ends of C1 dropping to 70% of initial value will be at least extended .

[0043] The following uses a specific case to introduce the scheme in detail:

[0044] As shown in Figure 5 , one end of the resistor R1 in the R / C delay circuit is grounded, and the other end is connected in series with the anode of the Zener diode D2; the cathode of the Zener diode D2 is connected to Vin and the anode of the Zener diode D1; the cathode of the Zener diode D1 is connected to Vout; the power supply Vcc is connected in series with the anode of the diode D3 and one end of the capacitor C1, and the other end of the capacitor C1 is grounded; the input end of the DC-DC conversion chip is connected to the cathode of the diode D3, and the output end of the DC-DC conversion chip is connected to Vout; the output power of the DC-DC boost converter comes from a separate super capacitor;

[0045] Before EN is valid, the DC-DC boost converter is in standby state, and the internal PWM power consumption is small, at the order of uA.

[0046] After power failure, the enable end EN is high level effective, and the DC-DC boost converter PWM power consumption is about 1mA, which is equivalent to connecting a 3kΩ resistor in parallel between C1 and GND. The working voltage IN and the enable end EN maintain effective for about 0.36*(R4 / / 3k)*C1≈0.35 ms. Example 2

[0047] As shown in Figure 4 , one end of the resistor R1 in the R / C delay circuit is grounded, and the other end is connected in series with the anode of the Zener diode D2;

[0048] The cathode of the Zener diode D2 is connected to Vin and the anode of the Zener diode D1; the cathode of the Zener diode D1 is connected to Vout;

[0049] The power supply Vcc is connected in series with the anode of the diode D3 and one end of the capacitor C1, and the other end of the capacitor C1 is grounded;

[0050] The input end of the DC-DC conversion chip is connected to the cathode of the diode D3, and the output end of the DC-DC conversion chip is connected to Vout; the output power of the DC-DC boost converter comes from a separate super capacitor;

[0051] The first end of the collector of the triode Q1 is connected with the cathode of the diode D3 after being connected with the resistor R3 in series, and the second end is connected with the enable end of the DC-DC conversion chip and the MCU INT; the base of the triode Q1 is connected with the anode of the zener diode D2 after being connected with the resistor R2 in series; and the emitter of the triode Q1 is grounded.

[0052] The capacitor C1 is increased, the energy storage of the power supply VCC is provided, the diode D3 is connected in series for isolating the reverse discharge current, and the holding time of the high level of the EN and the working voltage IN is prolonged.

[0053] The unidirectional conductivity of the diode is utilized, after the power supply is powered off, the VCC is rapidly reduced, the voltage between the two ends of the capacitor C1 is higher than the VCC side, the diode D3 is cut off, the triode Q1 is almost cut off, the discharge current of the capacitor C1 is small, the discharge time of the capacitor C1 is greatly prolonged, when the collector of the triode Q1, the EN end, the MCU INT end and the impedance of the three parts in parallel are Rin, the equivalent load resistance of the IN end of the DC-DC boost converter is RL, then the time constant is ;

[0054] Under the condition that the PWM working voltage IN of the DC-DC boost converter is high enough, after the EN high level is effective, the DC-DC boost converter enters the soft start, and delays for a time If the voltage of the EN end is still higher than the minimum effective voltage value, then the DC-DC boost converter successfully boosts the output, the electric energy stored in the super capacitor is converted through the boost, the working power supply of the circuit is supplemented, and the working time of the communication module is prolonged. Embodiment 3

[0055] The utility model provides a kind of application of power supply power failure detection and boost conversion circuit, use the power supply power failure detection and boost conversion circuit in embodiment 1 is applied in intelligent electric meter communication module, from the moment of power failure of power grid, to super capacitor starts to supply power to circuit, the electric quantity stored in the large filter capacitor on each working power supply between temporarily provides the energy of normal working of circuit.

[0056] A capacitor is increased in the embodiment to supplement the energy storage of the power supply of power failure detection circuit, a resistance or diode is increased to reduce reverse discharge, and the effective duration of DC-DC boost enable and PWM working voltage is prolonged. Embodiment 4

[0057] The utility model provides a kind of power supply power failure detection and boost conversion device, including the power supply power failure detection and boost conversion circuit in embodiment 1, and the power failure detection and boost conversion of power supply are carried out.

[0058] In the embodiment, the low cost is used to solve the small probability event of DC-DC boost conversion failure after power supply power failure, and safety redundancy is provided.

[0059] The embodiments of the present application are described in detail above with reference to the drawings, but the present application is not limited thereto, and various changes can be made within the knowledge of those skilled in the art without departing from the spirit of the present application.

Claims

1. A power supply brown-out detection and boost conversion circuit, characterized in that, comprising: at least one DC-DC boost converter, a capacitor C1 and a brown-out detection and boost circuit based on Zener diode; the capacitor C1 is connected in the circuit to provide energy storage for the power supply VCC for brown-out detection, and to prolong the effective time of the high level of EN and the working voltage IN. The capacitor C1 is connected in the circuit to form an R / C delay circuit or a D / C delay circuit. In the R / C delay circuit, one end of the resistor R1 is grounded, and the other end is connected in series with the anode of the Zener diode D2. The cathode of the Zener diode D2 is connected to Vin and the anode of the Zener diode D1; the cathode of the Zener diode D1 is connected to Vout.

2. The power fail detector and boost converter circuit of claim 1, wherein, The power supply Vcc is connected in series with the resistor R4 and one end of the capacitor C1, and the other end of the capacitor C1 is grounded.

3. The power fail detector and boost converter circuit of claim 2, wherein, The power input end IN of the DC-DC boost converter is connected to the output end of the resistor R4, and the output end of the DC-DC boost converter is connected to Vout. The output power of the DC-DC boost converter comes from a separate super capacitor. The first end of the collector of the transistor Q1 is connected to the output end of the resistor R4 after being connected in series with the resistor R3, and the second end is connected to the enable end of the DC-DC boost converter and the MCU INT; the base of the transistor Q1 is connected to the anode of the Zener diode D2 after being connected in series with the resistor R2; and the emitter of the transistor Q1 is grounded. The capacitor C1 is added to provide energy storage for the power supply VCC for brown-out detection, and the resistor R4 is connected in series to limit the discharge current, prolonging the effective time of the high level of EN and the working voltage IN. In the D / C delay circuit, one end of the resistor R1 is grounded, and the other end is connected in series with the anode of the Zener diode D2. The cathode of the Zener diode D2 is connected to Vin and the anode of the Zener diode D1; the cathode of the Zener diode D1 is connected to Vout.

4. The power fail detector and boost converter circuit of claim 3, wherein, The power supply Vcc is connected in series with the anode of the diode D3 and one end of the capacitor C1, and the other end of the capacitor C1 is grounded.

5. The power fail detector and boost converter circuit of claim 2, wherein, The power input end of the DC-DC boost converter is connected to the cathode of the diode D3, and the output end of the DC-DC boost converter is connected to Vout; the output power of the DC-DC boost converter comes from a separate super capacitor. The first end of the collector of the transistor Q1 is connected to the cathode of the diode D3 after being connected in series with the resistor R3, and the second end is connected to the enable end of the DC-DC boost converter and the MCU INT; the base of the transistor Q1 is connected to the anode of the Zener diode D2 after being connected in series with the resistor R2; and the emitter of the transistor Q1 is grounded. The capacitor C1 is added to provide energy storage for the power supply VCC for brown-out detection, and the diode D3 is connected in series to isolate the reverse discharge current, further prolonging the holding time of the high level of EN and the working voltage IN. The power supply brown-out detection and boost conversion circuit according to any one of claims 1-6 is used for brown-out detection and boost conversion of the power supply. ​ 6. The power fail detector and boost converter circuit of claim 5, wherein, ​ 7. A power failure detection and boost converter device, characterized in that, ​

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