RU2066915C1 - Power control device - Google Patents

Abstract

FIELD: microelectronics; control of electric devices incorporating filament, including electric lamps, or those incorporating electric motor, including fans. SUBSTANCE: to control power transmitted to resistive or inductive loads, base-collector junctions of first and second p-n-p transistors are connected into diode bridge in series with first and second diodes; transistor bases are connected to diode anodes, collectors are connected, respectively, to first and second power leads and emitters, to thyristor control inputs. EFFECT: enlarged functional capabilities, improved reliability of power control. 4 dwg

Description

 The invention relates to microelectronics and can be used to control electrical appliances having an electric filament, including an electric bulb, or containing an electric motor, including fans.

 A known electronic regulator circuit (patent SU 1820986, A3), which allows you to adjust the power given to the load.

 The operation of the circuit is based on the principle of phase adjustment of power: the circuit generates a sawtooth voltage on the capacitance, synchronized with the frequency of the AC 220 V; control voltage is applied to another control input; when comparing these voltages, the comparator either actively holds the thyristors in the closed state, or turns them on; after switching on, the thyristors are actively turned off after the phase of the mains voltage passes through zero.

 The disadvantage of this circuit is the impossibility of its inclusion in series with the load (three outputs input, output, common), and the inability to control inductive loads (since in this circuit the thyristors are actively closed after the phase of the mains voltage passes through zero, namely at this moment the current through inductive load reaches its maximum value).

 The proposed device is a two-wire by the method of inclusion, that is, it is connected in series with the load and can be structurally combined, for example, with a switch. Also, the absence of active locking of the thyristors allows you to use this device to adjust the power supplied to the inductive load, since after the phase of the mains voltage passes through zero, the thyristors will remain open until the current completely passes through the inductive load.

 The inventive device is connected in series with a load of terminals 1 and 2, contains two thyristors 7 and 8 connected in opposite-parallel, and a controlled voltage to current converter 15, the operation modes of which are set by at least two external capacitors connected to the control inputs 3, 4 and 5, 6. Capacities connected to the control inputs determine the open or closed state of the thyristors. The capacitors are charged and the thyristors 1 and 2 are turned on by a controlled voltage to current converter 15 through decoupling diodes 16 and 17, and the discharge is carried out by two PNP conductivity transistors 13 and 14 connected to two arms of the diode bridge with diodes 9, 10, 11, 12 .

 In FIG. 1 shows a structural diagram of a device for power control (URM), in FIG. 2 shows timing diagrams of its operation; FIG. 3 shows the scheme of practical inclusion.

 The URM contains two thyristors 7 and 8, connected counter-parallel between the power terminals 1 and 2, a controlled voltage to current converter 15 with inputs 5 and 6 of the control element connected, powered by a diode bridge with diodes 9, 10, 11 and 12 connected between the power conclusions 1 and 2. The output of the controlled voltage to current Converter 15 through decoupling diodes 17 and 16 is connected to the inputs 3 and 4 of the control of the thyristor elements 7 and 8, respectively. The control inputs 3 and 4 are also connected to emitters of transistors 13 and 14 of P-N-P-type conductivity, the base-collector junctions of which are connected in series with diodes 9 and 10 of the two arms of the diode bridge.

 The device operates as follows.

 When thyristors 7 and 8 are closed, when the mains voltage is applied, the controlled voltage-to-current converter 15 will be powered through the diode bridge (diodes 9, 10, 11, 12) and the output driver is a current of magnitude I. The current level is determined by the level of control voltage at the control input 5 relative to pin 6 and can be installed by an external control element (resistor or capacitance).

 In FIG. 3, the level is set by the capacitance C3, in FIG. 4 potentiometer R.

 If at a given moment of time a more positive voltage is applied to terminal 1 than to terminal 2, then the output current of the controlled converter 15 will charge the capacitance C2 (in Fig. 3) connected to the input 3 of the thyristor 7. The current to power the controlled converter will flow through terminal 1, transistor 14 of the PNP type of conductivity, diode 10, controlled converter 15, diode 11 and terminal 2 of the URM.

 The transistor 14 capacitance C1 (figure 3) will be maintained in the discharged state.

 When the voltage on the capacitance C2 rises to a level corresponding to the opening threshold of the thyristor 7, the latter will turn on and will pass current to the load. The controlled Converter 15 is shunted by the thyristor 7, which remains on until the end of the half-cycle of the mains voltage (or until the end of the current flow during operation on an inductive load).

где t время задержки включения тиристора;
0,7 порог [B] открывания тиристора;
I_вых15 выходной ток управляемого преобразователя 15;
С2 значение емкости С2.Thus, the controlled Converter 15 using the capacitance C2 will form a delay on the thyristor 7. When the threshold for opening the thyristor 0.7 V, the delay on is defined as

where t is the delay time of the thyristor;
0.7 threshold [B] thyristor opening;
I _{och15 the} output current of the controlled Converter 15;
C2 is the value of capacitance C2.

 After the voltage between terminals 1 and 2 changes its polarity, i.e. the voltage at terminal 2 will become more positive than at terminal 1, the thyristor 7 will turn on in the opposite direction and will not pass current, and the diode bridge from the diodes 9, 10, 11 and 12 will begin to power the controlled converter 15. Current will flow through terminal 2 , base-collector junction of the transistor 13, diode 9, controllable converter 15, diode 12, pin 1.

 The capacitance C2 connected between the terminals 3 and 2 (in Fig. 3) will begin to be discharged by the transistor 13; capacitance C1 connected between terminals 4 and 1 (in Fig. 3) will begin to be charged with the output current of the controlled converter 15, and after a time t (formula 1), the voltage across it will reach the threshold level of thyristor 8. The thyristor will turn on and begin to pass current to the load and shunts the controlled transducer.

 Thus, at one half-wave of the mains voltage, one of the capacitors is charged and turns on the thyristor with the necessary delay, the other capacitance is discharged by one of the additional transistors included in the diode bridge arm, and the functions of the capacitors change at the other half-wave.

 Resistors R4 and R5 are used to discharge capacitances C1 and C2 (figure 3) when the device is disconnected from the network.

 The controlled voltage-to-current converter 15 consists of a secondary voltage source (resistor R1, Zener diode D1 and transistors T1, T2 and T3), a supply current generator (resistor R2, transistors T4, T5 and T6, diode D2), and the voltage-to-current converter itself ( transistors T7, T8, resistor R3) and a reflective current generator (transistors T9, T10). Converter 15 operates as follows. A rectified mains voltage (via rectifier diodes 9, 10, 11, 12) is supplied to the secondary voltage source, from which it generates a voltage of 6.3 V (at the emitter of transistor T1 relative to terminal 6). The supply generator sets the outgoing current of the input 6 of the controlled voltage to current converter by the collector T5 (diode D2 serves to exclude the reverse input current, which would discharge the capacitance C3 in Fig. 3.1, when the thyristors 7 and 8 are closed and, accordingly, the secondary power source does not form 6 , 3 V), and also feeds the converter itself with the collector current of the T6 transistor. The voltage-to-current converter itself consists of an emitter follower on transistors T7 and T8 (the voltage on the emitter T8 repeats the voltage at input 5), and the current is determined by the value of the resistor R3. The reflective current generator converts the collector current of the transistor T8 into the flowing collector current of the transistor T10.

 For normal operation of the URM, it is necessary to determine the minimum and maximum output current of the controlled voltage-to-current converter.

 The minimum current should provide a delay of the thyristor on longer than a half-period of the mains voltage.

According to formula 1, at C1 C2 1.0 μF, U _pore 0.7 V, t 10 ms the output current of the controlled Converter 15 should be about 70 μA.

 The maximum current will determine the minimum turn-on delay of the thyristor, which remains at the maximum level of control voltage at input 5.

At the maximum current I _o15max , for example, 0.7 mA (10 times more than I _o15min ), the turn-on delay will be 10 times less than the half-period, i.e. about 1 ms.

 In FIG. 2a is a timing diagram of the mains voltage.

 In FIG. 2b shows a timing diagram of the voltage change across capacitance C2, in FIG. 2c, the change in voltage at the capacitance C1. For time T + and T- there corresponds the value of control current I (thick line), for time T + 'and T-' the value of control current I '(thin line), with T +> T +', T-> T- 'and, accordingly, I <I '.

 In FIG. 2d shows a time diagram of the voltage across the load for two values of the control currents I and I '.

 In FIG. 4 presents a diagram of the practical inclusion of the URM, which provides power control during operation on the active (electric lamp) and inductive (electric fan motor) loads.

 In FIG. 3 presents a diagram of the practical inclusion of the URM, which allows you to smoothly turn on and off the electric lamp. The inclusion process will occur as follows. When the key K1 is opened, the capacitance C3 will smoothly charge from a certain minimum voltage to a maximum (these levels are determined by the outgoing current of the input of the controlled converter and the value of the resistor R). In this case, the output current of the controlled converter 5 gradually increases and, accordingly, the turn-on delay of thyristors 7 and 8 decreases with each period. This ensures a smooth increase in the power transmitted to the load. The soft start time is regulated by changing the capacitance C3 and ranges from tenths of a second (to protect the lamp from burnout) to several seconds (visual perception of smoothness). In the process of smooth switching on when the key K1 is closed, the capacitance will be discharged with a time constant determined by the difference between the discharge time constant of the capacitance C3 through the resistor R and the charge time constant by the outgoing input current of the controlled converter, which can also take several seconds to visualize the smoothness of switching off.

Claims (1)

 A device for power control, containing the first and second thyristors connected in parallel between the first and second power terminals, a diode bridge from the first, second, third and fourth diodes, also connected between these terminals, a controlled voltage-to-current converter with an input connected to conclusions for connecting a control signal, the output of which through the fifth and sixth diodes is connected to the control inputs of the corresponding thyristors, while the control transitions of the thyristors are shunted by capacitors, about characterized in that the base-collector junctions of the first and second pnp-type transistors are connected in series with the first and second diodes, the bases of the transistors being connected to the anodes of the diodes, the collectors are connected respectively to the first and second power output, and the emitters are connected to the control inputs thyristors.

Images