A DALI bus power supply and temperature compensation method thereof

Abstract

The present invention provides a DALI bus power supply, comprising a power supply input, a voltage stabilizing circuit, a constant current circuit connected to the positive electrode of the voltage stabilizing circuit, an output positive electrode, and an output negative electrode. The constant current circuit comprises a transistor Q1, a Darlington transistor Q2, a resistor R1, a resistor R2, a resistor R3, and a negative temperature coefficient thermistor RT1. The emitter of the Darlington transistor Q2 is connected to the positive electrode of the voltage stabilizing circuit via the resistor R1, and the base of the Darlington transistor Q2 is connected to the negative electrode of the voltage stabilizing circuit via the resistor R3. The collector of Darlington transistor Q2 is connected to the positive output electrode, the emitter of transistor Q1 is connected to the positive electrode of the voltage stabilizing circuit, the base of transistor Q1 is connected to the positive electrode of the voltage stabilizing circuit via resistor R1 after being connected in parallel with the emitter of Darlington transistor Q2 via resistor R2, the collector of transistor Q1 is connected to the negative electrode of the voltage stabilizing circuit via resistor R3 after being connected in parallel with the base of Darlington transistor Q2, and the negative temperature coefficient thermistor RT1 is connected between the emitter of transistor Q1 and the base of transistor Q1. The present invention is simple, low in cost and good in performance.

Description

[Technical field]

[0002] The present invention relates to the field of circuit technology, and in particular to a DALI bus power supply and a temperature compensation method thereof. [Background technology]

[0004] LED (light emitting diode), known as "green lighting", has attracted much attention. Compared with traditional light sources, LED has the characteristics of being green and environmentally friendly, small in size, low in power consumption, and long in life, making it very suitable for use as a light source for lamps.

[0005] DALI (Digital Addressable Lighting Interface) is a new control protocol for intelligent lighting systems. As an internationally open lighting control communication protocol, DALI has been widely used in various lighting projects due to its simple structure, easy installation, easy operation, and excellent functions.

[0006] Due to the application technology update, the DALI bus power supply may be able to power the sensor (CC load) while taking into account the DALI BUS communication power supply function (CV load). However, after carrying CC load for a long time, the temperature of the power supply will increase and the output current will decrease.

[0007] A related technology is to add a large area heat sink to the power tube in the constant current circuit to reduce the overall temperature rise of the power supply. However, when the ambient temperature rises, the internal temperature of the power supply will also increase, thereby reducing the accuracy of the output current. Traditional technology leads to large product size, high cost and cannot completely solve the problem of low output current accuracy.

[0008] Another related technology is that the constant current circuit is at the negative pole of the power supply output, which may cause problems for some devices that cannot share the same ground with the power supply. At the same time, there will also be problems with poor current accuracy.

[0009] Therefore, it is necessary to provide a new DALI bus power supply and a temperature compensation method thereof to solve the above technical problems. [Summary of the invention]

[0011] The object of the present invention is to provide a DALI bus power supply capable of outputting high-precision current and a temperature compensation method thereof, so as to solve the problems in the related art.

[0012] In order to achieve the above-mentioned object, the present invention provides a DALI bus power supply, which includes a power input, a voltage stabilizing circuit connected to the power input, a constant current circuit connected to the positive electrode of the voltage stabilizing circuit, an output positive electrode, and an output negative electrode. The constant current circuit includes a transistor Q1, a Darlington transistor Q2, a resistor R1, a resistor R2, a resistor R3, and a negative temperature coefficient thermistor RT1. The emitter of the Darlington transistor Q2 is connected to the positive electrode of the voltage stabilizing circuit via the resistor R1, and the base of the Darlington transistor Q2 is connected to the negative electrode of the voltage stabilizing circuit via the resistor R3. The collector of the Darlington transistor Q2 is connected to the output positive electrode, the emitter of the transistor Q1 is connected to the positive electrode of the voltage stabilizing circuit, the base of the transistor Q1 is connected to the positive electrode of the voltage stabilizing circuit via the resistor R1 after being connected in parallel with the emitter of the Darlington transistor Q2 via the resistor R2, the collector of the transistor Q1 is connected to the negative electrode of the voltage stabilizing circuit via the resistor R3 after being connected in parallel with the base of the Darlington transistor Q2, and the negative temperature coefficient thermistor RT1 is connected between the emitter of the transistor Q1 and the base of the transistor Q1.

[0013] More preferably, the transistor Q1 is a PNP transistor, and the Darlington transistor Q2 is a PNP Darlington transistor.

[0014] More preferably, the constant current circuit further includes a diode D1 connected in series with the collector of the Darlington transistor Q2.

[0015] More preferably, the constant current circuit further includes a capacitor C1 connected in parallel with the resistor R2, and the capacitor C1 is used to adjust the feedback speed of the transistor Q1.

[0016] More preferably, the constant current circuit further includes a capacitor C2 connected in parallel to the output positive electrode and the output negative electrode, and the capacitor C2 is used to eliminate noise.

[0017] In order to achieve the above-mentioned object, the present invention also provides a temperature compensation method for a DALI bus power supply, which includes a power input, a voltage stabilizing circuit connected to the power input, a constant current circuit connected to the positive electrode of the voltage stabilizing circuit, an output positive electrode, and an output negative electrode. The constant current circuit includes a transistor Q1, a Darlington transistor Q2, a resistor R1, a resistor R2, a resistor R3, and a negative temperature coefficient thermistor RT1. The emitter of the Darlington transistor Q2 is connected to the positive electrode of the voltage stabilizing circuit via the resistor R1, the base of the Darlington transistor Q2 is connected to the negative electrode of the voltage stabilizing circuit via the resistor R3, the collector of the Darlington transistor Q2 is connected to the output positive electrode, the emitter of the transistor Q1 is connected to the positive electrode of the voltage stabilizing circuit, the base of the transistor Q1 is connected to the positive electrode of the voltage stabilizing circuit via the resistor R2 and then connected to the positive electrode of the voltage stabilizing circuit via the resistor R1, and the transistor The collector of the transistor Q1 is connected in parallel with the base of the Darlington transistor Q2 and then connected to the negative electrode of the voltage stabilizing circuit via the resistor R3. The negative temperature coefficient thermistor RT1 is connected between the emitter of the transistor Q1 and the base of the transistor Q1. When the temperature is normal, if the current output by the voltage stabilizing circuit increases, the collector voltage of the transistor Q1 increases, which reduces the collector voltage of the Darlington transistor Q2, thereby controlling the current to become smaller and realizing the constant current process. When the temperature rises, the collector voltage of the transistor Q1 increases, resulting in a decrease in the collector voltage of the Darlington transistor Q2, a decrease in the output current, a decrease in the resistance of the negative temperature coefficient thermistor RT1, an increase in the base voltage of the transistor Q2, a decrease in the collector voltage of the transistor Q1, an increase in the collector voltage of the Darlington transistor Q2, and an increase in the output current, thereby completing the temperature compensation process.

[0018] More preferably, the transistor Q1 is a PNP transistor, and the Darlington transistor Q2 is a PNP Darlington transistor.

[0019] More preferably, the constant current circuit further includes a diode D1 connected in series with the collector of the Darlington transistor Q2.

[0020] More preferably, the constant current circuit further includes a capacitor C1 connected in parallel with the resistor R2, and the capacitor C1 is used to adjust the feedback speed of the transistor Q1.

[0021] More preferably, the constant current circuit further includes a capacitor C2 connected in parallel to the output positive electrode and the output negative electrode, and the capacitor C2 is used to eliminate noise.

[0022] The technical effect of the present invention is as follows: by setting the constant current circuit at the output positive pole, the problem that many docking systems cannot share a common ground is solved; the constant current circuit uses the Darlington transistor Q2 as the main power control tube, which has a large output current and is easy to control; in addition, a negative temperature coefficient resistor is used to perform temperature compensation for the temperature drift of the transistor Q1, thereby solving the problem of poor output current accuracy caused by the temperature drift of the transistor Q1.

Brief Description of the Drawings

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work, among which:

[0025] Figure 1 is a block diagram of a DALI bus power supply of the prior art;

[0026] Figure 2 It is a structural block diagram of a DALI bus power supply of the present invention. [Specific implementation method]

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] like Figure 1 As shown, a DALI bus power supply 100' of the prior art includes a power input, a voltage stabilizing circuit 1', a constant current circuit 2' connected to the negative pole of the voltage stabilizing circuit 1', a positive power output, and a negative power output. The prior art sets the constant current circuit 2' at the negative pole of the voltage stabilizing circuit 1', but this will cause some devices to be unable to share the same ground with the power supply and cause problems.

[0030] like Figure 2 As shown, a DALI bus power supply 100 of the present invention includes a power input, a voltage stabilizing circuit 1 connected to the power input, a constant current circuit 2 connected to the voltage stabilizing circuit, an output positive electrode OUT+, and an output negative electrode OUT-. The output positive electrode OUT+ and the output negative electrode OUT- can be connected to a load.

[0031] The constant current circuit 2 includes a transistor Q1 , a Darlington transistor Q2 , a resistor R1 , a resistor R2 , a resistor R3 , and a negative temperature coefficient thermistor RT1 .

[0032] The emitter of the Darlington transistor Q2 is connected to the positive electrode of the voltage stabilizing circuit 1 via the resistor R1, the base of the Darlington transistor Q2 is connected to the negative electrode of the voltage stabilizing circuit 1 via the resistor R3, and the collector of the Darlington transistor Q2 is connected to the positive electrode OUT+ of the power output.

[0033] The emitter of the transistor Q1 is connected to the positive electrode of the voltage stabilizing circuit 1, the base of the transistor Q1 is connected in parallel with the emitter of the Darlington transistor Q2 via the resistor R2 and then connected to the positive electrode of the voltage stabilizing circuit 1 via the resistor R1, and the collector of the transistor Q1 is connected in parallel with the base of the Darlington transistor Q2 and then connected to the negative electrode of the voltage stabilizing circuit 1 via the resistor R3.

[0034] In this embodiment, transistor Q1 is a PNP transistor, and Darlington transistor Q2 is a PNP Darlington transistor. The function of transistor Q1 is as a current detection device, and the function of Darlington transistor Q2 is as a main power control tube. Transistor Q1 can control Darlington transistor Q2, and transistor Q1 and Darlington transistor Q2 are combined into a negative feedback circuit, and the function of the negative feedback circuit is constant current.

[0035] The function of resistor R1 is to detect current. Resistor R1 and the load are connected in series, and the current flowing through the load is equal to the current flowing through resistor R1.

[0036] The negative temperature coefficient thermistor RT1 is connected between the emitter of the transistor Q1 and the base of the transistor Q1. The negative temperature coefficient thermistor RT1 is used to provide temperature compensation for the temperature drift of the transistor Q1.

[0037] The constant current circuit 2 further includes a diode D1 connected in series with the collector of the Darlington transistor Q2. The diode D1 is an isolation diode. Because multiple power supplies may be connected in parallel when in use, the diode D1 can isolate the power supplies from affecting each other.

[0038] The constant current circuit 2 further includes a capacitor C1 connected in parallel with the resistor R2. The function of the capacitor C1 is to adjust the feedback speed of the transistor Q1.

[0039] The constant current circuit 2 further includes a capacitor C2 connected in parallel between the output positive electrode OUT+ and the output negative electrode OUT-, which functions to eliminate high-frequency noise.

[0040] The working principle of a DALI bus power supply 100 of the present invention is:

[0041] If the output load is normal,

[0042] Phase 1: After the power input is powered on, the voltage regulator circuit 1 will output a stable voltage, and the output current of the Darlington transistor Q2 is equal to the collector current of Q2, that is, the current at point E. Since the Darlington transistor Q2 is connected in series with R1, the output current is also equal to the current flowing through R1. When the output current increases, a voltage drop signal is generated between points A and B at both ends of the resistor R1. Since the voltage at point A is greater than the voltage at point B, and point B is connected to the base of the transistor Q1 through the resistor R2, the base voltage of the transistor Q1 will also decrease. When the difference between the base voltage of the transistor Q1 and point A reaches the threshold value for the transistor Q1 to be turned on, the transistor Q1 will be turned on, and the voltage at point D will increase. Point D is connected to the base of Darlington transistor Q2. When the base voltage of Darlington transistor Q2 increases, the collector voltage of Darlington transistor Q2 will decrease, that is, point E and the output voltage will decrease, thereby reducing the load current. In this way, the constant current circuit 1 completes a constant current process.

[0043] Phase 2:

[0044] When the power supply is continuously loaded, the temperature of the entire environment increases. When the temperature of transistor Q1 rises, transistor Q1 will produce temperature drift, and its amplification factor will increase, causing the voltage at point D to rise, thereby reducing the output current of Darlington transistor Q2. As the internal temperature of the power supply increases, the temperature of the negative temperature coefficient thermistor RT1 will also increase, thereby reducing the resistance of RT1, the voltage at point C will increase, the voltage at point D will decrease, the voltage at point E will increase, and the output current will increase, thus completing the temperature compensation process.

[0045] The collector current of Darlington transistor Q2 is designed to be greater than the normal output current, so the temperature increase of Darlington transistor Q2 can be achieved by designing the current margin, and the output current detection of the power supply is controlled by transistor Q1.

[0046] Compared with the prior art, a DALI bus power supply 100 of the present invention sets a constant current circuit at the output positive pole to solve the problem that many docking systems cannot share a common ground. In addition, the constant current circuit uses a Darlington transistor Q2 as a main power control tube, and its output current is large and easy to control. In addition, a negative temperature coefficient resistor is used to compensate for the temperature drift of the transistor Q1, which solves the problem of poor output current accuracy caused by the temperature drift of the transistor Q1. Therefore, the present invention has the advantages of simplicity, low cost and good performance.

[0047] The present invention provides a temperature compensation method for a DALI bus power supply 100, which includes a power input, a voltage stabilizing circuit 1 connected to the power input, a constant current circuit 2 connected to the positive electrode of the voltage stabilizing circuit 1, an output positive electrode OUT+, and an output negative electrode OUT-. The constant current circuit 1 includes a transistor Q1, a Darlington transistor Q2, a resistor R1, a resistor R2, a resistor R3, and a negative temperature coefficient thermistor RT1. The emitter of the Darlington transistor Q2 is connected to the positive electrode of the voltage stabilizing circuit 1 via the resistor R1, the base of the Darlington transistor Q2 is connected to the negative electrode of the voltage stabilizing circuit 1 via the resistor R3, the collector of the Darlington transistor Q2 is connected to the output positive electrode OUT+, the emitter of the transistor Q1 is connected to the positive electrode of the voltage stabilizing circuit 1, the base of the transistor Q1 is connected to the positive electrode of the voltage stabilizing circuit 1 via the resistor R2 and then connected to the positive electrode of the voltage stabilizing circuit 1 via the resistor R1, the collector of the transistor Q1 is connected to the base of the Darlington transistor Q2 in parallel and then connected to the negative electrode of the voltage stabilizing circuit 1 via the resistor R3, and the negative temperature coefficient thermistor RT1 is connected between the emitter of the transistor Q1 and the base of the transistor Q1. When the temperature is normal, if the current output by the voltage stabilizing circuit 1 increases, the collector voltage of the transistor Q1 increases, which reduces the collector voltage of the Darlington transistor Q2, thereby controlling the current to become smaller and realizing the constant current process; when the temperature rises, the collector voltage of the transistor Q1 increases, causing the collector voltage of the Darlington transistor Q2 to decrease, the output current to decrease, the resistance of the negative temperature coefficient thermistor RT1 to decrease, and the base voltage of the transistor Q2 to increase, which reduces the collector voltage of the transistor Q1, increases the collector voltage of the Darlington transistor Q2, and increases the output current, thereby completing the temperature compensation process.

[0048] Compared with the prior art, a temperature compensation method for a DALI bus power supply 100 of the present invention sets a constant current circuit at the output positive pole to solve the problem that many docking systems cannot share a common ground. Moreover, the constant current circuit uses a Darlington transistor Q2 as a main power control tube, and its output current is large and easy to control. In addition, a negative temperature coefficient resistor is used to perform temperature compensation for the temperature drift of the transistor Q1, thereby solving the problem that the temperature drift of the transistor Q1 causes poor output current accuracy. Therefore, the present invention has the advantages of simplicity, low cost and good performance.

[0049] Finally, it should be noted that the above embodiments are only intended to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A temperature compensation method for a DALI bus power supply, comprising a power input, a voltage stabilizing circuit connected to the power input, a constant current circuit connected to the positive electrode of the voltage stabilizing circuit, an output positive electrode, and an output negative electrode, characterized in that: The constant current circuit includes a transistor Q1, a Darlington transistor Q2, a resistor R1, a resistor R2, a resistor R3, and a negative temperature coefficient thermistor RT1. The emitter of the Darlington transistor Q2 is connected to the positive electrode of the voltage stabilizing circuit via the resistor R1, the base of the Darlington transistor Q2 is connected to the negative electrode of the voltage stabilizing circuit via the resistor R3, the collector of the Darlington transistor Q2 is connected to the output positive electrode, the emitter of the transistor Q1 is connected to the positive electrode of the voltage stabilizing circuit, the base of the transistor Q1 is connected to the positive electrode of the voltage stabilizing circuit via the resistor R2 and then connected to the positive electrode of the voltage stabilizing circuit via the resistor R1, and the collector of the transistor Q1 is connected to the base of the Darlington transistor Q2 in parallel and then connected to the negative electrode of the voltage stabilizing circuit via the resistor R3. The negative temperature coefficient thermistor RT1 is connected between the emitter of the transistor Q1 and the base of the transistor Q1. When the temperature is normal, if the current output by the voltage stabilizing circuit increases, the collector voltage of the transistor Q1 increases, which reduces the collector voltage of the Darlington transistor Q2, thereby controlling the current to become smaller and realizing the constant current process; when the temperature rises, the collector voltage of the transistor Q1 increases, resulting in a decrease in the collector voltage of the Darlington transistor Q2, a decrease in the output current, a decrease in the resistance of the negative temperature coefficient thermistor RT1, and an increase in the base voltage of the transistor Q2, which reduces the collector voltage of the transistor Q1, increases the collector voltage of the Darlington transistor Q2, and increases the output current, thereby completing the temperature compensation process.

2. A temperature compensation method for a DALI bus power supply according to claim 1, characterized in that: The transistor Q1 is a PNP transistor, and the Darlington transistor Q2 is a PNP Darlington transistor.

3. A temperature compensation method for a DALI bus power supply according to claim 2, characterized in that: The constant current circuit further includes a diode D1 connected in series with the collector of the Darlington transistor Q2.

4. A temperature compensation method for a DALI bus power supply according to claim 3, characterized in that: The constant current circuit further includes a capacitor C1 connected in parallel with the resistor R2 , and the capacitor C1 is used to adjust the feedback speed of the transistor Q1 .

5. A temperature compensation method for a DALI bus power supply according to claim 4, characterized in that: The constant current circuit further includes a capacitor C2 connected in parallel to the output positive electrode and the output negative electrode, and the capacitor C2 is used to eliminate noise.

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