RU2810265C2 - Ultra-low power source control circuit - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: invention relates namely to control circuits with ultra-low power consumption and is intended to create low-power AC-DC power supplies without an auxiliary winding on a power transformer. The technical result, which the claimed technical solution is aimed at achieving, is achieved by introducing a step-up voltage converter into the circuit, which converts the operating power supply of the circuit into an increased voltage. The output transistor driver's power is connected to the circuit's operating power and boost voltage through a multiplexer controlled by a comparator. The comparator controls the operating power of the circuit and controls the internal transistor, which is connected between the source of the power transistor and the common wire. The anode of the diode is connected to the common point of the transistors, the cathode of which is connected to the operating power bus of the circuit.

EFFECT: reducing losses in the control circuit of the power source, increasing the efficiency of low-power sources.

2 cl, 2 dwg

Description

The ultra-low power consumption control circuit is designed to create low-power AC-DC power supplies without an auxiliary winding on the power transformer. The annual decisions of the Energy Conservation Commission of the European Parliament and the Council tighten the requirements for energy consumption from electrical networks and regulate: the quality of energy consumed, efficiency in the operating load range from 10% to 100%, as well as idle consumption [1].

A device is known, described in the patent [2] in which, in the transformer 510 (Fig. 5) there is an additional winding 513, as well as a diode D7 and a capacitor C4, which allow the control device to be powered from a reduced voltage, which achieves a reduction in losses in the control circuit, with In this case, the starting resistor R3 is not turned off. This circuit has two disadvantages: the need to use additional winding and rectifier elements, and that the starting resistor is not turned off and its nominal value is a compromise between the turn-on time of the power supply (it is desirable to have a low resistance) and the constant power dissipation in operating mode (it is desirable to have a high resistance ).

The device described in the patent [3] is also known, in which, despite a different circuit design, the disadvantages of the above device are preserved.

The device described in the patent [4] is also known, in which an additional winding is also used, but a switch is introduced into the circuit that allows you to turn off the starting circuits and thereby reduce the power losses in the control circuits. There are known products with such a control circuit that dissipate less than 15 mW [5].

Products with such a control circuit are known [6]. As a rule, they allow operation in two modes as described in patents [7] and [8].

The closest technical solution is the patent [7], issued by the World Intellectual Property Organization and its Russian analogue [8], containing 4 independent and 19 dependent claims and 5 illustrations in which, in clauses 8 and 21, circuits for controlling power from an additional winding and the ability to work without it. The operation of the circuit is given in the description, from which it is clear that in the absence of an additional winding, the control device is powered through the starting switch S2. The disadvantage of this scheme is that the entire control current passes through the starting switch and the power loss on it is

where P _d power losses, P ₀ - power in the control circuit, V _in - input supply voltage, V _сс - supply voltage of the control circuit and in real circuits the power losses are 50-100 times higher than the power in the control circuits, which is only permissible in low-power sources nutrition.

The technical result of the proposed invention is to reduce losses in the control circuit of the power source.

The technical result is achieved by the fact that a step-up voltage converter is introduced into the circuit, converting the operating power of the circuit into an increased voltage, and the power supply of the output transistor driver is connected to the operating power of the circuit and the increased voltage through a multiplexer controlled by a comparator, which controls the operating power of the circuit and controls the internal transistor, which is connected between the source of the power transistor and the common wire, the anode of the diode is connected to the common point of the transistors, the cathode of which is connected to the operating power bus of the circuit.

Implementation of a control circuit for an AC-DC power supply with ultra-low power consumption containing a circuit power unit with an initial start-up unit that provides operating power to the circuit, a reference voltage source, a controller that implements a particular power supply control algorithm, a feedback signal receiver, and an output transistor driver to which an external output power transistor is connected, as well as a step-up voltage converter that converts the operating power of the circuit into an increased voltage, the output transistor driver power is connected to the operating power of the circuit and the increased voltage through a multiplexer controlled by a comparator, which controls the operating power of the circuit and controls the internal transistor, which is connected between the source of the external output power transistor and the common wire, the anode of the diode is connected to the common point of the transistors, the cathode of which is connected to the operating power bus of the circuit, allows you to exclude from the circuit the additional winding of the power transformer and the power supply system of the control circuit associated with it, which significantly simplifies and reduces the cost of the power supply circuit.

An example of the implementation of a power supply circuit is shown in Figure 1. The circuit contains: a control circuit made according to this invention (1) with two filter capacitors C1 and C2, a feedback unit with galvanic isolation (2), a power transformer TR1, an external high-voltage transistor VT1 and an output rectifier with filter VD1 and C4.

The circuit should fundamentally be one of the variants of a flyback converter, and in which in the first cycle, with transistor VT1 open, energy is accumulated in the transformer

where =Lt and It are the inductance and current of the transformer, respectively, and in the second cycle the energy is transferred to the filter capacitor C4 and then to the load.

Figure 2 shows a block diagram of the control device. The circuit contains: (1) - a control device microcircuit, which includes - a starting unit (5), a supply voltage control circuit (14), an external storage capacitor (16), a reference voltage source (13), an FB feedback unit (17) , power supply controller (7), comparator (12), internal transistor (11), internal diode (10), external output power transistor driver (8), boost voltage converter (4) and multiplexer (6), external capacitors (15) and (16) and an external output power transistor (9).

The scheme works as follows:

Start of the circuit: when turned on, the input voltage Vin is supplied to the starting block StUp (5) and the external capacitor C1 of the power supply to the control circuit Vcc1 begins to charge. When the voltage reaches 2.5-3 V, the supply voltage control circuit turns on a step-up voltage converter made, for example, on internal switched capacitors, and an increased voltage Vcc2 appears on capacitor C2. When the voltage Vcc1 reaches 6 V, the Vin power is turned off and the control circuit goes into operating mode.

Operating mode: the operating mode of the control circuit is provided by the power supply controller PowerControl (7) together with the feedback node FB (17), which implements one or another power supply control algorithm, for example, PWM. To implement ultra-low power consumption by the control circuit and ensure stable power supply to Vcc1, a comparator Cmp (12) is introduced into the circuit, which controls the supply voltage of the control circuit and when the value of Vcc1 drops below 5.7 V, it closes transistor VT2 (11) and switches the supply voltage of the output transistor driver VT1 (8) using multiplexer MX (6) to increased voltage Vcc2. Through the diode VD2 (10), the external capacitor C1 begins to charge and at Vcc = 6 V the circuit returns to its original state. The inductive reactance of the primary winding of the transformer limits the charging current of capacitor C1, and the energy accumulated in the transformer is transferred to the load.

Power balance: we determine the ratio of energies transferred to capacitor C1 and to the load during one pulse of duration Ti. Energy in capacitor E _C

Where Vin/Lt is the rate of current rise in the transformer,

Energy in the transformer.

The energy ratio is determined by the formula

Those. the ratio is the same in formula 1), except that the energy of the transformer does not turn into waste heat, but goes into the load, thereby increasing the efficiency of low-power power supplies.

With a typical control circuit power of 4-6 mW, the minimum load should be at least 300 mW.

This control circuit is recommended for use in low-power power supplies installed in devices that, due to their characteristics, consume at least 300 mW in standby/operating mode, for example, climate control systems with a large number of various micro-consumption sensors.

Literature

1) Official Journal of the European Union COMMISSION REGULATION (EU) 2019/1782 of 1 October 2019.”

2) US Patent 2020/0287454.

3) US Patent 9,705,408.

4) US Patent 9,712,045.

5) Data Sheet “Off-Line PWM Controllers with Integrated Power MOSFET STR6A100xV/xVD Series”.

6) Description of the chip “Green Mode Power Switch FSL206MR” www.onsemi.com

7) WO 2009/146141 A1 dated 29 May 2008 “Primary side control circuit and method for ultra-low idle power operation))

8) RU 2456736 C1.

Claims (2)

1. An AC-DC power supply control circuit with ultra-low power consumption, containing a circuit power unit with an initial start-up unit that provides operating power to the circuit, a reference voltage source, a controller that implements the power supply control algorithm, a feedback signal receiver, an external output transistor driver, to which an external output power transistor is connected, characterized in that a step-up voltage converter is introduced into the circuit, converting the operating power of the circuit into an increased voltage; the power supply of the driver of the external output power transistor is connected to the operating power of the circuit and the increased voltage through a multiplexer controlled by a comparator that controls the operating power supply of the circuit and controls the internal transistor, which is connected between the source of the external output power transistor and the common wire; the anode of the diode is connected to the common point of the transistors, the cathode of which is connected to the operating power bus of the circuit. 2. AC-DC power supply control circuit according to claim 1, characterized in that the output power transistor is structurally included in the circuit.

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