RU153218U1 - SECONDARY POWER SUPPLY WITH ELECTRICALLY DISCONNECTED CONTROL - Google Patents

Abstract

1. Secondary power supply with galvanically isolated control, consisting of a primary converter unit or a converter unit, a secondary converter unit, a transformer for power transmission and galvanic isolation between the input and output circuits or a choke for energy transfer between the input and output circuits, a stabilization circuit by current or voltage at the output, the output node of the reference signal required for external or internal regulation of the output parameters, characterized in that it contains an interface block that provides galvanically isolated analog or combined analog and pulse-width control with a given function of transferring the level of the input control signal to reference output node 2. The secondary power supply with galvanically isolated control according to claim 1, characterized in that it contains an additional auxiliary power winding for the interface unit, which provides a linear function of transferring the level of the input control signal to the reference signal output node and consists of a stabilizer of the reference voltage source and an interface with interchange. 3. The secondary power supply with galvanically isolated control according to claim 2, characterized in that the linear gain of the output signal from the level converter circuit of the input control signal to the reference signal output node is provided by using optocoupler isolators with the same transfer characteristics and parameters in the circuit of the decoupled interface. 4. Secondary power supply galvanically isolated�

Description

This utility model relates to the field of electrical engineering, in particular to regulated or controllable switching power supply devices that contain functions for external control. One of the promising and dynamically developing areas of technical application is lighting equipment, as well as other areas of application where it is required to provide adjustment of the output parameters of the power source from the level of the input control signal in the entire required range. The development trend of energy-saving technologies and the integration of power supplies into automated systems and processes require operational monitoring and control of the operation modes of various devices. In today's market, power supplies with an external control function are widely represented, which allows you to change the output parameters of the power source (current, voltage or power) in accordance with a given external signal level. In the field of lighting technology, the generally accepted standard of analog control 0 / 1-10 V or pulse-width control of a fixed frequency is used.

It is known that a power supply device and lighting equipment, including a power supply device (patent for invention RU No. 2442300 dated March 24, 2009, publ. 02/10/2012, IPC Н05В 37/02). The power source device comprises means for generating a direct current power output for receiving alternating current power, converting alternating current power into direct current power and delivering direct current power, a semiconductor light emitting element that is supplied with direct current power provided from the direct current power generating means, and emits light and control means for receiving a signal for decreasing light intensity and controlling the output of direct current power from the means If the output current of the direct current power is in accordance with the signal for decreasing the luminous intensity, the control means controls the means for generating the output power of the direct current to reduce the light intensity and ignite or suppress the semiconductor light emitting element, discontinuing the control of the direct current power, based on the signal of decreasing the light intensity for a predetermined a period of time starting with a time reference immediately after AC power is applied.

Also known is the Method and circuit of a dimmable LED driver (US 20140167634 A1 publ. 06/19/2014, IPC Н05В 37/02). An LED driver, comprising: a transformer having a primary side and a secondary side, the primary side is configured to transmit energy to the secondary side in response to an input signal, and on the secondary side configured to provide output current in one or more LEDs by an amount corresponding to the amount of energy transferred to the secondary side. A current control loop configured to control the current in the primary winding so that the output current is equal to the reference current signal. A current control circuit configured to introduce a current control signal into the current control loop in response to a phase signal that biases a portion of the input signal and wherein the control current loop is further configured to reduce current in the primary winding sensitive to the current control signal so that the brightness of each LED connected to the secondary side is reduced by an amount corresponding to the value of the current adjustment signal.

The disadvantage of these power sources is the lack of analog or combined control with a linear dependence on the input signal level. The presence of an optocoupler isolator does provide galvanic isolation on the control circuit, however, the nonlinear characteristic of the optocoupler involves only pulse control, which significantly limits the functionality.

Closest to the proposed technical nature of the device is a power source and lighting equipment (patent for invention RU No. 2513548 dated March 24, 2009, published on April 27, 2012, IPC Н05В 37/02). A power source device, comprising: a semiconductor light emitting element, control means for receiving a light reduction signal indicating a light reduction depth, setting one of a current control mode and a voltage control mode based on the light intensity reduction depth and exciting a semiconductor light emitting element, wherein: current regulation means the regulation tool determines the target current based on the depth of reduction of light intensity and regulates the constant electron the current supplied to the semiconductor light emitting element to drive the semiconductor light emitting element in such a way that a constant electric current is maintained at the target current, and in the voltage control mode, the control means determines the target voltage based on the depth of reduction of the light intensity and adjusts the load voltage applied to the semiconductor light emitting element), which is supplied with a constant electric current to excite a semiconductor light a radiating element so that the load voltage is maintained at the target voltage.

Also very similar in technical essence can be considered Dimmable LED driver (US 20140042912 A1 publ. 02.13.2014, IPC Н05В 33/08). A device for dimming at least one load, the device comprising: a power source having an output voltage. Many driver channels are connected to the voltage output of the power supply, each of which has a load at the output and a controller having many channels for setting the current value, each of which is connected to one of the multi-channel driver circuits, characterized in that the channel of the driver circuit is configured to control the output current at the load at the set value. The disadvantage of these analogues is that there is a direct galvanic connection between the control device and the output of the power source along the reference signal reference circuit. Various transients, breakdowns and discharges, as well as the appearance of high potentials in the load associated with the “mass” with the output of the control device, significantly reduces reliability and stability, and can also lead to premature failure of the equipment.

The technical problem, which the claimed model is aimed at, is to create a power source devoid of the disadvantages of the presented analogues and prototypes and capable, unlike prototypes, of providing galvanic isolation on the control circuit, thereby increasing the level of protection of control devices, as well as providing analog or combined analogue - pulse-width control with a given function of transmitting the control input signal to the reference signal input.

The technical solution is aimed at eliminating these drawbacks and is achieved by the fact that an additional auxiliary power winding is introduced into the inductive energy storage element of the transformer or inductor (depending on the type of topology) of the switching power supply, providing galvanic isolation on the control circuit and the induction energy of which provides power to the block circuit interface input controls. The linear transmission coefficient of the output signal from the conversion circuit of the input pulse or analog control signal to the reference input signal is provided by the use of integrated elements with built-in galvanic isolation.

The technical result that provides the claimed utility model is the expansion of control functionality, providing a high level of fault tolerance and protection, as well as galvanic isolation of external control devices by "mass" and the input control signal connected to pulsed secondary power sources. A significant advantage of the presented solution is also the low cost of implementation and extended operational characteristics.

The utility model is illustrated by drawings:

in FIG. 1A shows a block diagram of a first embodiment of a power supply according to the present utility model;

in FIG. 1B shows a block diagram of a second embodiment of a power source according to the present utility model;

in FIG. 2 shows a block diagram of a third embodiment of a power supply according to the present utility model;

in FIG. 3 shows a simplified electrical schematic diagram of an interface unit;

in FIG. 4A and FIG. 4B shows graphs of the dependence of the output signal from the circuitry of the interface unit depending on the level and types of the input control signal;

in FIG. 5 shows a simplified electrical schematic diagram of a modification of the interface unit.

The best embodiment of a power supply for a common flyback topology is shown in FIG. 1A, includes a pulse transformer 14 with a primary winding 14a and a secondary winding 14b (for the implementation of a multi-channel output, a secondary winding 14c or more is assumed), which provides energy transfer and galvanic isolation between the circuits of the input and output connected to the windings. The primary block of the transformer 10 is connected to the primary winding of the transformer, which, as a rule, in the classic version consists of a PWM (pulse-width modulation) controller, a transistor power switch, a rectifier, electromagnetic interference suppression filters, etc. The main unit of the source 7 is powered by a DC or AC voltage source 9. An output DC voltage 13.1 is generated at the output of the secondary unit of the converter 12 connected to the terminals of the secondary winding 14b. The output from the stabilization circuit 13 by current or voltage is connected directly to the load 12. The output node of the reference signal 11, which is required for internal or external regulation by the output parameters of the power source, is controlled by a constant voltage according to the signal level Vout generated from the output of the interface node with isolation 16 in the composition interface unit 17. The stabilizer source of OH (reference voltage) 15 connected to the terminals of the auxiliary auxiliary winding power ISO, generates a supply voltage for the circuit of the interface unit with junction 16 at the control input.

In the following description, the old reference numbers indicate the same parts as in FIG. 1A, and their description will not be repeated.

It is known that for the construction of switching power supplies there are also PWM controllers (the English name is Primary Side Regulated Flyback Controllers), which provide stabilization of the output parameters in the load by controlling the current and voltage along the primary circuit of the pulse transformer converter. In this case, the structural diagram of the power source as part of the main unit 5 with the interface unit 17 for external isolated control takes on the form shown in Fig.1B. Similarly, the output node of the reference signal 11 is controlled by the level of the signal Vout, as in the source embodiment in FIG. 1.A and the principle of implementing isolated control does not change. The device and composition of the third embodiment of the power supply of the present utility model shown in FIG. 2, represent the structural layout for the topologies for building switching power supplies of the Buck type, Boost or Buck-Boost type, while there is no galvanic isolation between the input circuits and the load 12. In this case, the provision of galvanic isolation of the main unit 6 of the power supply for control proposed by this utility model becomes more relevant. The composition and operation of the device are largely identical to the variant in Fig. 1A, except for the presence of a inductor (inductor) 22a on the core 22 and converter unit 8. In the presented embodiment, the auxiliary power winding ISO is introduced directly to the core of the inductor 22. During operation, the induction energy with the windings of the inductor 22a on the ISO winding also feeds the interface unit 17. Moreover, the general essence of the operation of the interface unit 17 in this design also does not change and is similar to the versions of the sources in FIG. 1A and FIG. 1B.

It is worth noting that for the technical result, as an alternative to the galvanically isolated supply element for the interface unit 17, a DC / DC converter can be connected to the output of the secondary converter 13.1, the output of which will be connected to the input of the OH 15 source stabilizer, excluding the presence of an auxiliary ISO power winding, however, such a solution would be more expensive.

A simplified circuit diagram of the interface unit 17 is shown in FIG. 3. The incoming control signal Vin from the output of the control device 18 is limited by the level of the protective zener diode VD1 and then goes to a non-inverting primary conversion circuit that implements a linear transfer function and consists of an operational amplifier (op-amp) DD2.1, a resistor R4 in positive feedback, the output voltage divider R8-R9 in negative feedback and the divider R2-R3 connected to the reference potential UREF.

The source stabilizer OH 15 contains a circuit of elements of a pulse rectifier VD2 and a capacitor C3 at the terminals of the ISO winding to form an auxiliary DC supply voltage, which is then supplied to a regulating transistor VT1 (an emitter follower included in the circuit) and a parametric thermocompensated stabilizer on a DD4 chip (for example, chip TL431). The supply voltage VCC of the interface unit with isolation 16 is fixed by a value determined by the level of control voltage to DD4 coming from the divider R14 and R15. The stabilizer current DD4 and the base current of the transistor VT1 is limited by the resistor R13, the value of which is selected by the minimum operating current of the stabilizer DD4. Similarly, the parametric stabilizer (consisting of DD6, VT2, R19, R17 and R18) of the supply voltage VDD from the output 13.1 of the converter unit 8 or the secondary unit of the converter 12. From the output of the op-amp DD2.1, the control signal then goes to the temperature stabilization circuit and limits the maximum the level of the input signal Voutmax to the input of the OS DD2.2. The maximum voltage level Vout max corresponding to the value of the input voltage Vinmax is also fixed by a parametric stabilizer on a DDI chip (for example, similar to DD4) and is determined by the level of the control voltage coming from the divider R6 and R7.

The level of the reference bias voltage UREF required for the primary converter circuit at the op-amp DD2.1 is formed by a resistor R16 that sets the stabilization current of the DD5 chip (for example, similar to DD4).

In the presented embodiment of the circuit of the interface unit 16, optocoupled isolators DD7 and DD8 with the same transfer characteristics and parameters are used. At the output of the operational amplifier (op amp) DD2.2, the maximum flow current in the sequential direct connection circuit of the LEDs of the optocouplers DD7 and DD8 is limited by the resistor RIO, and the radiation fluxes generated by the LEDs of the optocouplers DD7 and DD8 are equal. To compensate for the nonlinearity of the LED elements of the optocouplers DD7 and DD8, an output voltage from the resistor R11 is supplied to the inverting input of the op-amp DD2.2 in the negative feedback circuit, the level of which is determined by the flowing current from the emitter of the phototransistor DD7.

The voltage at the output of the op-amp DD2.2 with negative feedback continuously strives to ensure that the potential at the inverting input is equal to the potential at the non-inverting input, which allows to obtain a linear transfer coefficient between the input voltage level at the positive input of the op-amp DD2.2 and the output voltage levels on resistors R11 and R12. By setting the values of the resistors R11 and R12 equal, as well as the supply voltage of the VCC and VDD interface unit, a single transfer coefficient K = 1 is achieved, i.e. The galvanic isolation circuit operates in repeater mode Vout = Vin. The indicated variant of the interface circuit of the interface unit 16 is a cheap way of decoupling with a linear characteristic, however, it partially retains the nonlinearity and drift and accuracy of the transmission coefficient inherent in optocouplers. To minimize distortion and drift of the transmission coefficient and bias, the values of the resistors R11 and R12 are selected within tens of ohms. The maximum isolation voltage is limited by the breakdown voltages of the optocouplers and the insulation of the auxiliary power winding ISO. A plot of the reference reference output signal Vout as a function of the control input signal Vin is shown in FIG. 4A. The required accuracy, total power consumption and thermal stability of the transmission coefficient K is determined by the tolerance and characteristics of the elements used in the circuit.

An alternative to the use of optocoupler isolators can also be decoupling buffer amplifiers with modulation-demodulation (MDM) or isolating operational amplifiers. At the same time, the presence of an additional auxiliary ISO power winding is not excluded.

In order to isolate the DC component from the Vin signal in the case of pulse-width-pulse control (PWM), two low-pass filters R1-C1 and R5-C2 are provided, the first of which suppresses external high-frequency noise, and the second directly forms a constant level. For the example of FIG. 4B shows a graph of the time dependence of the output signal of the reference signal Vout from the input Vin in the case of PWM control with a duty cycle of Q pulses of 50%.

Various versions of the interface unit 16 as part of the circuit of the interface unit 17 allow you to convert the level and combine analog and pulse-width control methods with different coefficients and transmission functions of the input signal level.

There are other modifications of the proposed device that do not affect the essence of the proposed utility model. For example, in a modification of the power supply device of FIG. 5, as part of the interface unit 17, there is a microcontroller 19 and an interface module 20. This design allows the implementation of digital control algorithms both according to the analog level of the input signal Vin, and in the format of various communication protocols based on the popular DALI, RS485 exchange interfaces, etc.

The test results of the current secondary power source based on the proposed solution showed high performance, namely the stability of the output parameters and a wide range of operating temperatures.

Claims (4)

1. A secondary power supply with galvanically isolated control, consisting of a primary converter unit or converter unit, a secondary converter unit, a transformer for energy transfer and galvanic isolation between the input and output circuits or a choke for transferring energy between the input and output circuits, stabilization circuits current or voltage output, the output node of the reference signal required for external or internal regulation of the output parameters, characterized in that it contains bl ok interface, which provides galvanically isolated analog or combined analog and pulse-width control with a given function of transmitting the level of the input control signal to the output node of the reference signal. 2. The secondary power source with galvanically isolated control according to claim 1, characterized in that it contains an additional auxiliary power winding for the interface unit, which provides a linear function of transmitting the level of the control input signal to the reference signal output node and consists of a stabilizer of the reference voltage source and node interfacing with interchange. 3. The secondary power source with galvanically isolated control according to claim 2, characterized in that the linear transmission coefficient of the output signal from the circuit of the level converter of the input control signal to the output node of the reference signal is provided by the use of optocoupler isolators with the same transfer characteristics and parameters in the circuit of the interface node with denouement. 4. A secondary power source with galvanically isolated control according to claim 3, characterized in that the interface unit includes a microcontroller and an interface module for implementing digital control algorithms, both by analogue level of the input signal and in the format of various exchange protocols based on popular sharing interfaces.

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