TWI238591B - Power supply capable of providing stable procedure-controlled power output - Google Patents

Abstract

The present invention is related to a kind of power supply capable of providing stable procedure-controlled power output, in which a transformer is disposed at the DC output terminal of the power supply. The two-phase of the transformer connects to a clamping circuit. Because the clamping circuit is disposed at the two-phase of the step-down transformer, no high DC voltage tolerance is required to drive the clamping circuit to operate. In addition, the clamping circuit can clamp in advance the high-voltage that the drain bears as the MOSFET (metal oxide semiconductor field effect transistor) is at the OFF state so as to decrease the high voltage born by the MOSFET to improve the reliability of MOSFET. Moreover, the energy, which generates and stores in the transformer due to magnetic leakage and inductance, can be released or eliminated so as to further prevent transformer saturation.

Description

1238591 V. Description of the invention Q) '' " ---- Technical field to which the invention belongs: This = Ming is a kind of power supply that can provide stable program control power output for two kinds-by means of the clamping circuit (Clamping Circuit) and The two large sides are connected, so that when the metal-oxide-semiconductor half-field-effect transistor is in the 0ff state, the high voltage that it can withstand can be clamped in advance by the clamping circuit, so that the metal-oxide-semiconductor half-field effect transistor can withstand the high voltage. The voltage is reduced to increase the reliability of the metal-oxide half-field effect transistor. Prior technology: According to the general test object, a switching power supply is widely used to provide the required power. Traditionally, the power supply required to provide the test object is mostly a linear power supply. Linear power supplies are often used in power supplies that can provide a constant voltage or current, and provide low ripple noise (low ripple noise), low, avoid interference, L ο ϊ; Ε Μ I) , Good full knot characteristics, easy to control and many other advantages. Although the linear power supply has been widely accepted by the general user in the market, it still has some disadvantages, such as large power loss and low power efficiency. Furthermore, due to the large size and low efficiency of power supplies, it has become an inevitable trend to use switching-mode techniques to make power supplies and to provide power density and power efficiency. The traditional switching power supply, as shown in Figure 1, uses the circuit's conduction and wear and tear to repeatedly change the DC voltage after the input voltage is rectified and filtered to a certain frequency, and the result is filtered, that is, can

1238591 V. Description of the invention (2) Obtain a fixed output voltage instead of a voltage output that varies with program control. Generally speaking, switching power supplies are high-frequency electronic devices, and their operating frequencies are currently between 20KHz and 200KHz. In the system circuit, its power switch, such as a transistor or metal-oxide-semiconductor field-effect transistor (MOSFET), will work in the characteristic region of saturation and cut off (fut). The traditional linear power supply usually uses a transistor that works in the linear region and uses it as a varistor to adjust the unstable input voltage. In this type of circuit, the passive component must bear the current that changes with the load. Once the input voltage changes or the load suddenly increases, the power consumed by the passive component changes or increases accordingly. As a result, the power lost to the entire system increases and the efficiency decreases. However, the switching power supply does not fully work in the linear region. Therefore, even if the input voltage range varies widely and the load varies greatly, it can still obtain higher efficiency than the linear power supply. Furthermore, please refer to Figure 2. It is a flyback power supply circuit. Because its transformer doubles as an output energy storage inductor, and only one diode D1 is required on the secondary side, and C1 is mainly Used to adjust the power factor of the power supply. Furthermore, the poWer stage consisting of PW M 1C and Q1 'T1 is mainly obtained by controlling the conduction of the Q1 electronic switch by PWM 1C, and then cooperating with the diode D1 and capacitor C 0 on the secondary side The output of DC voltage, but because the transistor Q 1 is on, there will be a primary current flowing on the primary side of the transformer T 1, but because the polarity of the primary side and the secondary side of the transformer T 1 is opposite, the diode D 丨

Page 6 1238591 V. Description of the invention (3) It is reverse biased and has no energy output, so it is impossible to control the opening and closing cycle of the PWM IC through the feedback circuit; moreover, the current is stored in the transformer Ding 1, causing the transformer T1. Large loss. In addition, the transformer may have a clamping circuit (C 1 am ping C ircuit) at the beginning of the transformer to clamp the voltage passing through the current, but because the primary current voltage is higher, the efficiency will be lower than the original, and the clamping circuit ( Clamping circuit) components must withstand high voltage, so the cost is higher than general. Please refer to Figure 3, which is a forward power circuit. The main difference from the flyback circuit is the secondary side of the Power st age. The forward type uses one Schottky II. The stage body and inductor, when Q 1 is turned off, the voltage polarity on the winding of the isolation transformer T1 will be reversed, so that the D2 diode body becomes reverse bias and does not conduct, while the D3 secondary body is in a conducting state, at this time the load The end energy is supplied by the energy stored in L 0 and C 0 through D 3. Therefore, in the topology of the 顋 direction 弍 circuit; LG and C0 are not only low-pass filters, but also an energy storage element. The use of components is similar to that of the Flyback circuit. However, since the reverse voltage from the primary side of T1 when transistor Q2 is turned OFF, the output voltage on C0 is accumulated and becomes twice the output voltage. It has a voltage of more than 800V, and although the forward power circuit can make the current flowing through the primary and secondary sides of the transformer smaller, the copper loss of the transformer is small, but the transformer adds a third winding, which increases the cost .

IHHI 1238591

V. Description of the invention (4) Summary of content: The inventor has accumulated manufacturing experience and technology in view of the aforementioned changes in the conventional input voltage or load sudden power changes or increases, and the efficiency decreases accordingly. The needle method, after continuous research, an invention of the invention that can provide a stabilizer, the power supply circuit (Clamping Circuit) circuit can be the high voltage and instantaneous storage The discharge 'makes the reliability of the oxygen half field effect transistor. Once the linear power supply is increased, the power consumed by the passive components to the entire system is also accompanied by the disadvantages. It is based on the research on the power supply to study the above-mentioned shortcomings and various solution experiments and improvements. A clamp is connected to the secondary side of the transformer for the power supplied by the program-controlled power supply. The clamp circuit (the high voltage that can be withstood due to the energy stored in the transformer due to the magnetic leakage of the transformer when the Clamping Crystal is OFF) increases the invention One purpose is to provide a differential program control IC at the DC output terminal of the power supply of the present invention that can provide stable program control power output. 俾 Through the comparison function of the differential program control IC, the output of the DC output terminal The voltage is compared with a preset voltage / time v (t) program, and the difference after the comparison is transmitted to a pulse width adjustment integrated circuit (PWM 1C) through an optical coupler (Opto Coupler), The pulse width adjustment integrated circuit is controlled to control a metal-oxide-semiconductor field-effect transistor (M0SFET) at the input end of the power supply according to the difference. ON (OFF) load cycle, so as to adjust the current switching (ON-OFF) time of the input power flowing into the primary side of one of the transformers of the power supply, so that the DC output of the power supply can provide

• I 1238591 fi, description of the invention (5) " a ^ ---- a preset program controls the output of stable current. Another object of the present invention is that the power supply of the present invention that can provide stable program-controlled power output is provided with a voltage dividing circuit, and the voltage dividing circuit is connected to a DC power source of a rectifier / filter circuit at the input end of the power supply. "The voltage divider circuit is connected to the input terminal of the pulse width adjustment integrated circuit chip. /" When the voltage applied to OVRV exceeds the set value due to the AC power being too high, "" can make the metal oxygen half field effect power The crystal is turned off (the operation is suspended), so that the power supply is protected from being damaged by high voltage, and at the same time, the bias circuit required for the primary drive circuit of the transformer can be provided. Another object of the present invention is to provide The invented power supply capable of providing stable program-controlled power output is provided with a snubber circuit. The snubber circuit is connected to the metal-oxide half field effect transistor. The snubber circuit can prevent the snubber circuit. When the transformer is turned off in the metal-oxide-semiconductor half-field-effect transistor, the pulse high voltage caused by the reverse of the voltage on the primary side of the transformer may affect the metal-oxide-semiconductor half-field effect transistor. Breakdown damage, its working principle is that when the metal oxide half field effect transistor 0FF, the high voltage pulse generated on the primary side of the transformer? By charging a capacitor, you can slow down the instantaneous voltage change to preserve the metal oxygen half field Effect transistor and reduce the generation of magnetic interference signals; when the metal oxide half field effect transistor is turned on (the diode is forward biased), the energy stored in the capacitor is discharged by the capacitor, and it is originally due to the pulse current. The energy stored in the capacitor is consumed.

1238591 V. Description of the invention (6) 'Method of implementation: The present invention is a power supply that can provide stable program-controlled power output. Please refer to Figures 4 and 5. The power supply 20 mainly includes a rectifier / Wave-reduction circuit 2], a transformer 22 ', a double-wave circuit, and a DC output terminal 24, wherein the rectification / filter circuit 21 is connected to an AC power source 31 of a city electricity, and the capacitor C2 and the inductor u are used to form the circuit. The full-wave rectification / sine wave circuit 'rectifies and filters the AC power supply 3 1 to obtain a more stable DC power supply, and the transformer 22 is connected to the rectification / filtering circuit 2 1' to cause it to rectify and cross-wave, and The AC power source modulated by the program-controlled switching circuit is reduced in its voltage value, and after the secondary filtering by the secondary filtering circuit 23, DC power is output from the DC output terminal 24. In addition, as shown in Figs. 4 and 5, a differential program control IC 25 is provided between the DC output terminal 24 and the secondary filter circuit 23 of the power supply 20, and the ratio of I C2 5 is controlled through the differential program. For the function, the output voltage of the DC output terminal 24 i is compared with the voltage / time V (t) program control set first, and the difference after the comparison is transmitted through an optical coupler (Opto Coupler) 26 To a pulse width adjustment control chip (PWM IC) 27, so that the pulse width adjustment control chip (PWM 1C) 27 controls one of the metal-oxide half field effect between the rectifier / filter circuit 2 1 and the transformer 2 2 according to the difference The waveform load period of the transistor (M0SFET) 28 adjusts the ratio of the current switching (0N-OFF) of the input power flowing into the primary side of the transformer 22, so that the DC output terminal 24 of the power supply 20 can provide the original setting. The voltage waveform is input in the present invention. Please refer to FIG. 4 and FIG. 5 for the power supply.

Page 10 1238591 V. Description of the invention (7)-One ~~ 20% has a voltage divider circuit 29 ', the voltage divider circuit 29 is connected to the rectifier / filter circuit 21 at the input end of the power supply, and the voltage divider The circuit 2 9 is connected to the pulse width adjustment control chip (PffM IC) 27, VRV terminal. The voltage dividing circuit 2 9 I transmits the DC power supply voltage of the rectification / filter circuit 2 丨 to the pulse width adjustment control chip. (PWM 1C) 27. When the voltage of OVRV is too high due to AC power, and the rectified DC voltage exceeds the set value, 0vrv can turn off the metal-oxide half field effect transistor 28 (0ff), so that the power supply The power supply 20 is protected from high voltage damage. In the present invention, please refer to FIG. 4 and FIG. 5. The power supply 20 is provided with a snubber circuit 210. The snubber circuit 210 is composed of a capacitor C4, resistors R3, R1, and a two-pole. It is composed of body D3 (Diode). The snubber circuit 210 is connected to the metal oxide half field effect transistor (MOSFET) 28. The snubber circuit 210 can prevent the transformer 22 When the crystal (M0SFET) 28 is turned off (OFF), the pulse current and high voltage caused by the voltage inversion; when the metal oxide half field effect transistor (M0SFET) 2 8 is OFF, the diode is reverse biased at this time, the transformer 22 The high-voltage pulse generated by the primary side 22b is charged by a capacitor C4 to absorb the pulse current; when the metal-oxide-semiconductor field-effect transistor (MOSFET) 28 is turned on, the diode D3 is forward biased In addition, the capacitor C4 is discharged, and the pulse current energy is consumed to protect the metal-oxide-semiconductor field-effect transistor (MOSFET) 28 and reduce the generation of electromagnetic wave (EMI) interference signals. In the present invention, please refer to FIG. 4 and FIG. 5 again, the power supply 20 is provided with a clamping circuit ((: 1311 ^ 11 ^ (^ 1 ^ 1 ^ 1:) 211) through a transformer

Page 11 1238591 V. Description of the invention (8) Cross-linking, the clamping circuit (211) and the secondary side of the voltage regulator (22) are compared, so the circuit (ciaroping and cutting)

Ci = cui t) 21 1 The high factor generated when the metal-oxide half field-effect transistor is 28 ° Fft = magnetic leakage and inductance generated by the transformer 22 and stored in the transformer to release the energy by the immediate reaction through the cross-link, so that The high voltage experienced by the metal-oxide half-field effect 28 is reduced to increase the degree of the metal-oxide half-field effect transistor. 4 * In the present invention, please refer to FIG. 4 and FIG. 5. The clamping circuit 211 The energy release method is that when the metal oxide semi-effect transistor 28 OF F, one of its diodes is changed from the original reverse bias to the forward direction, and the Zener Diodes are reverse biased, so that When it exceeds the reverse rated reference voltage, the Zener diode

Diodes) self-discharge to release and eliminate energy, and at the same time, avoid the transformer 22 from being saturated. In the present invention, please refer to FIG. 4 and FIG. 5. The a terminal of the primary side of the transformer 22 is connected to the positive terminal after the rectification / filter circuit 21, and the negative terminal of the rectified circuit is connected to the common terminal. In the present invention, please refer to FIG. 4 and FIG. 5, the primary side 22b of the transformer 22 is connected to the Drain of the metal oxide half field effect transistor (MOSFET) 28, and the metal oxide The main effect of the half field effect transistor 28 is to intercept the DC voltage. In the present invention, please refer to FIG. 4 and FIG. 5, the secondary side of the transformer 22 is connected to the secondary filter circuit 23, and the secondary The filter circuit 23 includes a diode 30 and a filter capacitor 32.

Page 121238591 V. Description of the invention (9) In the present invention, please refer to FIG. 4 and FIG. 5. The driving power of the pulse width adjustment control chip (PWM 1C) 27 is rectified / filtered. The circuit 21 provides the voltage Vcc of the driving power input to the PWM control chip (PWM 1C) 27 through the step-down and voltage stabilizing circuit resistor R12, capacitor C7 and Zener Diodes Zl. And holding results. In the present invention, please refer to FIG. 4 and FIG. 5. The pulse width control chip (PWM 1C) 27 is fixed in frequency by a resistor R5. In the present invention, please refer to FIG. 4 and FIG. 5 again. The over-voltage protection of the AC voltage in turn is a voltage dividing circuit 29 composed of a resistor Rll (a, b), a capacitor C1, and a resistor R12. The voltage at the connection point of Rlla'Rllb is connected to the pulse width adjustment integrated circuit (PWM 1C) 27 controlled by OVRV. 俾 When the voltage of OVRV exceeds the set value because the AC power supply 31 is too high, OVRV can make gold oxygen The half field effect transistor (MOSFET) 28 is turned off (SWITCH OFF), so that the power supply 20 is protected. In the present invention, please refer to FIG. 4 and FIG. 5. The PDRV and NDRV on the pulse width adjustment control chip (PWM 1C) 27 pass the resistors R1 〇a and R 10b to the pulse width adjustment control chip (PWM 1C ) 27 ON and OFF voltage waveform rising and falling slope control, and the pulse width adjustment integrated circuit (PWM 1C) 27 signal is output to the gate of the metal oxide semiconductor field effect transistor (M0SFET) 28, so that the source ( The current from Source to Drain and the primary side of the transformer 22 is controlled by the gate voltage signal. In the present invention, please refer to FIG. 4 and FIG. 5. The bias current generated by the current through the metal-oxide-semiconductor field-effect transistor (M0SFET) 28 flows through the resistor R4.

Page 13 1235991 V. Description of the invention (ίο) To the current detection terminal ILMT of the pulse width adjustment control chip (PWM IC) 2 7. The pulse width adjustment control chip 2 7 is generated by the allowable voltage value preset by the ILMT. The current protection function prevents the load current of the metal oxide half field effect transistor (MOSFET) 28 and the transformer 22 from being too large. In the present invention, please refer to FIGS. 4 and 5 again, the transformer 22 may be a toroidal transformer, which has the advantages of increasing magnetic energy conversion efficiency and reducing magnetic leakage.

The above description is only the best embodiment of the present invention, but the structural features of the present invention are not limited to this. Any person skilled in the art can easily consider changes or modifications and reduce some circuits in the field of the present invention. The functions can be covered by the patent scope of the following case.

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Claims (1)

1238591 VI. Scope of patent application Scope of patent application: 1 · A write source supply that can provide stable program control power output. 'The power supply mainly includes a rectifier / filter circuit, a transformer, a secondary filter circuit, and a DC output terminal. The rectifier / filter circuit is connected to a mains (AC) power source of a city power supply, and uses its capacitance and inductance. The formed full-wave rectifier circuit rectifies and filters the AC power to obtain a more stable DC power source, and the transformer is connected to the rectifier / filter circuit. It reduces the voltage value of the rectified and filtered DC power source. Secondary The secondary wave of the wave circuit 'outputs the direct current from the output end of the DC wheel. It is characterized in that the power supply δ has a Clamping Circuit, the Clamping Circuit and the transformer's secondary Side-to-side connection, can this clamp circuit (Clam ping Circuit) turn off the high level generated by the Drain when the MOSFET is turned off, can it be clamped in advance and the transformer ’s magnetic leakage, inductance and The energy stored in the transformer is released, which reduces the high voltage experienced by the metal-oxide-semiconductor field-effect transistor (MOSFET) to increase the reliability of the metal-oxide-semiconductor field-effect transistor (MOSFET). 2. As described in item 1 of the scope of the patent application, the energy release method of the power supply device that can provide stable program-controlled power output is the Clamping Circuit, which is one of the metal oxide half field effect transistor 0FF. Diode changed from the original reverse bias to forward, so that when it exceeds the reverse rated reference voltage, it can discharge and dissipate energy by itself. At the same time, its Zener Diode It is also reverse biased to avoid transformer saturation. Page 161238591-__ VI. Application for patent scope 3, as described in item 1 of the scope of patent application, a power supply that can provide stable process power output, the DC input of its power supply ^^ between the secondary filter circuit It has a comparison function of differential program control Ic, 俾 2 program control 1C, which compares the output voltage at the DC output terminal ^ = the voltage / time v (t) set first, and compares the difference after the comparison by one. Opto Coupler to—Pulse Width IC—Differentially controls the waveform of the rectifier / filter circuit and one transistor (M0SFET) between the transformers The power supply has a large current +: :: 2. This transformer's current output terminal can provide a stable program 丄 == direct electrical appliances of the power supply, 1 Λ can provide a stable program control circuit, the voltage dividing circuit and the power supply Supply: The source supply 15 is provided with a voltage-dividing circuit. The voltage-dividing circuit should be rectified / filtered at the 15 input terminal by the pulse width adjustment control chip. controlled by ac ^^ Hrv, the voltage divider circuit can Chip, when the voltage voltage of 0VRV is transmitted to the pulse width adjustment control 0VRV can make the metal oxygen half field neodymium thunder 蚰 C power is too high and exceeds the set value, protection from high voltage Z break = closed, so that The power supply has obtained a power supply of 5 ° according to the scope of the patent application, and the stable power supply circuit (Snubber Circuit) can be provided as described above, wherein the power supply is provided with a buffer by a capacitor and a resistor. Composition, the snubber circuit (Snubber Circuit) street circuit (Snubber Circuit) and $ 17 page 1238591 6. Application scope of the patent The metal-oxygen half field effect transistor is connected, the snubber circuit can prevent the transformer When the oxygen half field effect transistor is closed (OFF), the pulse current caused by the reverse voltage; when the metal oxide half field effect transistor is OFF, the high voltage pulse generated by the primary side of the transformer is reversely biased by one of the diodes. A capacitor is charged by a resistor to offset the pulse current. When the metal-oxide half-field effect transistor is turned on, the diode is forward biased and the capacitor is discharged, which consumes the pulse current energy. Off to preserve mosfet transistor and reduce the generation of electromagnetic interference signals. Page 18