This application claims priority to Chinese Patent Application No. 201410622163.3 filed on Nov. 7, 2014, the contents of which are incorporated by reference herein.
The subject matter herein generally relates to a power supply system.
Operational Amplifier (OP) is usually powered on by a direct current (DC) power supply. The DC power supply converts an alternating current (AC) voltage to a DC voltage which is provided to the OP. The DC power supply cannot regulate the DC voltage, which may cause the OP failure.
Implementations of the present technology will now be described, by way of example only, with reference to the attached figures.
It will be appreciated that for simplicity and clarity of illustration, where appropriate, reference numerals have been repeated among the different figures to indicate corresponding or analogous elements. In addition, numerous specific details are set forth in order to provide a thorough understanding of the embodiments described herein. However, it will be understood by those of ordinary skill in the art that the embodiments described herein can be practiced without these specific details. In other instances, methods, procedures and components have not been described in detail so as not to obscure the related relevant feature being described. Also, the description is not to be considered as limiting the scope of the embodiments described herein. The drawings are not necessarily to scale and the proportions of certain parts may be exaggerated to better illustrate details and features of the present disclosure.
Several definitions that apply throughout this disclosure will now be presented.
The term “coupled” is defined as connected, whether directly or indirectly through intervening components, and is not necessarily limited to physical connections. The connection can be such that the objects are permanently connected or releasably connected. The term “comprising,” when utilized, means “including, but not necessarily limited to”; it specifically indicates open-ended inclusion or membership in the so-described combination, group, series and the like.
The two input terminals of the noise filter 110 are configured to receive a 220 volts alternating current (AC) voltage. One output terminal of the noise filter 110 is electrically coupled to an anode of the first diode D1 and a cathode of the second diode D2 via the thermal resistor 120. Another output terminal of the noise filter 110 is electrically coupled to an anode of the third diode D3 and a cathode of the fourth diode D4. A cathode of the first diode D1 is electrically coupled to a cathode of the third diode D3. Anodes of the second diode D2 and the fourth diode D4 are grounded.
The filter circuit 200 includes a fifth diode D5, a resistor R, and a capacitor C. An anode of the fifth diode D5 is electrically coupled to the resistor R and the capacitor C. A cathode of the fifth diode D5 is electrically coupled to the cathodes of the first diode D1 and the third diode D3.
The voltage decreasing circuit 300 includes a transformer T, a sixth diode D6, and a seventh diode D7. The transformer T includes an input winding M1, a first output winding M2, and a second output winding M3.
A first terminal of the input winding M1 is electrically coupled to the cathode of the fifth diode D5. The anode of the fifth diode D5 is electrically coupled to a second terminal of the input winding M1 via the resistor R. The anode of the fifth diode D5 is electrically coupled to the second terminal of the input winding M1 via the capacitor C. A first terminal of the first output winding M2 is electrically coupled to an anode of the sixth diode D6. A cathode of the sixth diode D6 is configured to output a +24 volts first direct current (DC) voltage. A second terminal of the first output winding M2 is grounded. A first terminal of the second output winding M3 is electrically coupled to the feedback circuit 400 via the seventh diode D7. A second terminal of the second output winding M3 is grounded.
The feedback circuit 400 includes a photoelectric coupler U1, a pulse width modulation (PWM) controller U2, a voltage regulating tube U3, and a variable resistor VR. The photoelectric coupler U1 includes a light emitting unit and a switch unit.
A first terminal of the variable resistor VR is electrically coupled to the cathode of the sixth diode D6. A second terminal of the variable resistor VR is grounded. An adjusting terminal of the variable resistor VR is electrically coupled to a cathode of the voltage regulating tube U3 and an adjusting terminal of the voltage regulating tube U3. The cathode of the voltage regulating tube U3 is electrically coupled to a cathode of the light emitting unit. An anode of the light emitting unit is electrically coupled to the first terminal of the variable resistor VR. An anode of the voltage regulating tube U3 is grounded. An emitter of the switch unit is electrically coupled to a cathode of the seventh diode D7. An anode of the seventh diode D7 is electrically coupled to the first terminal of the second output winding M3. A collector of the switch unit is electrically coupled to a control terminal of the PWM controller U2. An output terminal of the PWM controller U2 is electrically coupled to the second terminal of the input winding M1.
In use, the rectifier circuit 100 converts the 220 volts AC voltage to a +220 volts DC voltage which is provided to the input winding M1 of the transformer T. The transformer T decreases the +220 volts DC voltage to a +24 volts first DC voltage which is output by the first output winding M2. The second output winding M3 of the transformer T outputs a second DC voltage. The anode of the light emitting unit receives the +24 volts first DC voltage. The light emitting unit emits light. The switch unit detects the light from the light emitting unit and turns on. The control terminal of the PWM controller U2 receives the second DC voltage from the second output winding M3. The output terminal of the PWM controller U2 outputs PWM signals according to the second DC voltage. The filter circuit 200 filters the PWM signals which are provided to the input winding M1. The input winding M1 adjusts the +220 volts DC voltage according to a duty cycle of the PWM signals. The first output winding M2 of the transformer T outputs a stable first DC voltage.
In at least one embodiment, the adjusting terminal of the variable resistor VR is adjusted to change a regulating parameter of the voltage regulating tube U3. A current flowing through the light emitting unit is changed. Strength of the light emitted by the light emitting unit is changed. The duty cycle of the PWM signals is changed to adjust the first DC voltage slightly.
When the first output winding M2 outputs an over current, a voltage on the variable resistor VR decreases. A current flowing through the adjusting terminal of the voltage regulating tube U3 decreases. The current flowing through the light emitting unit also decreases. The strength of the light emitted by the light emitting unit is weakened. The switch unit turns off. The PWM controller U2 cannot receive the second DC voltage from the second output winding M3. The PWM controller U2 stops working The output terminal of the PWM controller U2 stops outputting PWM signals. The first output winding M2 of the transformer T stops outputting the first DC voltage.
The embodiments shown and described above are only examples. Many details are often found in the art such as the other features of a power supply system. Therefore, many such details are neither shown nor described. Even though numerous characteristics and advantages of the present technology have been set forth in the foregoing description, together with details of the structure and function of the present disclosure, the disclosure is illustrative only, and changes may be made in the detail, including in matters of shape, size and arrangement of the parts within the principles of the present disclosure up to, and including the full extent established by the broad general meaning of the terms used in the claims. It will therefore be appreciated that the embodiments described above may be modified within the scope of the claims.
Number | Date | Country | Kind |
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201410622163.3 | Nov 2014 | CN | national |