TWI817460B - Power supply device - Google Patents

Abstract

A power supply device provided. The power supply device includes a primary side circuit, a secondary side circuit, a controller, and a feedback and compensation circuit. The secondary side circuit generates a sensing voltage value according to an output current value. The feedback and compensation circuit provides a loop gain. When the sensing voltage value is greater than or equal to a reference value, the feedback and compensation circuit causes the controller to control the primary side circuit, so that the secondary side circuit provides an output voltage. When the sensing voltage value is less than the reference value, the feedback and compensation circuit causes the controller to perform a frequency reduction operation on the primary side circuit, and reduces the loop gain to reduce the voltage value of the output voltage.

Description

power supply unit

The present invention relates to a power supply device, and in particular, to a power supply device that can meet energy saving requirements under low load conditions.

In order to reduce the impact and impact of energy-consuming products on the environment, the European Commission's Energy-Saving Design Directive (2005/32/EC) has formulated a specification to stipulate energy-saving requirements for energy-consuming products in residential, tertiary industries and industrial sectors.

Regarding the power supply device, in order to reduce losses and save energy in a low load state (such as idle state or very light load state), the power supply device adopts a frequency reduction method (such as burst mode) to Reduce switching losses under low load conditions. However, in models with larger output power, there is still a limit to the loss reduction due to the larger energy. That is to say, under low load conditions, the output power has a reduction limit, and models with larger output power still cannot meet the energy saving requirements of the European Commission's Energy Saving Design Directive (such as Lot 7 external power supplies EC 278/2009 ).

The invention provides a power supply device that can meet energy saving requirements under low load conditions.

The power supply device of the present invention includes a power converter, a controller, and a feedback and compensation circuit. The power converter includes a primary side circuit and a secondary side circuit. The secondary side circuit generates a sensing voltage value based on the output current value. The controller is coupled to the primary side circuit. The feedback and compensation circuit is coupled to the secondary side circuit and the controller. Feedback and compensation circuitry provide loop gain. When the sensed voltage value is greater than or equal to the reference value, the feedback and compensation circuit enables the controller to control the primary side circuit, thereby causing the secondary side circuit to provide an output voltage. When the sensed voltage value is less than the reference value, the feedback and compensation circuit causes the controller to perform a frequency reduction operation on the primary side circuit, reducing the loop gain to reduce the voltage value of the output voltage.

Based on the above, when the sensed voltage value is less than the reference value, the feedback and compensation circuit reduces the loop gain of the power supply device to reduce the voltage value of the output voltage. Therefore, the output power can be reduced. In this way, under low load conditions, the power supply device can meet the energy saving requirements of current regulations.

In order to make the above-mentioned features and advantages of the present invention more obvious and easy to understand, embodiments are given below and described in detail with reference to the accompanying drawings.

Some embodiments of the present invention will be described in detail with reference to the accompanying drawings. The component symbols cited in the following description will be regarded as the same or similar components when the same component symbols appear in different drawings. These embodiments are only part of the present invention and do not disclose all possible implementations of the present invention. Rather, these embodiments are only examples within the scope of the patent application of the invention.

Please refer to FIG. 1 , which is a schematic diagram of a power supply device according to a first embodiment of the present invention. In this embodiment, the power supply device 100 includes a power converter CR, a controller 130 and a feedback and compensation circuit 140 . Power converter CR includes at least a primary side circuit 110 and a secondary side circuit 120 . The controller 130 is coupled to the primary side circuit 110 . The controller 130 controls the primary side circuit 110 so that the secondary side circuit 120 provides the output voltage VO. In this embodiment, the power converter CR also includes a transformer TR. Therefore, based on the control of the controller 130, the transformer TR, the primary side circuit 110 and the secondary side circuit 120 jointly convert the input voltage VI to generate the output voltage VO. The input voltage VI may be a rectified voltage signal. In this embodiment, the secondary side circuit 120 also generates the sensing voltage value VS according to the output current value IO. The output current value IO is directly related to the sensing voltage value VS.

In this embodiment, the feedback and compensation circuit 140 is coupled to the secondary side circuit 120 and the controller 130 . Feedback and compensation circuit 140 provides loop gain LG. The feedback and compensation circuit 140 receives the sensing voltage value VS from the secondary side circuit 120 and determines the sensing voltage value VS. When the sensing voltage value VS is greater than or equal to the reference value VR, it means that the output current value IO is higher than a current value level. The power supply device 100 is providing regular power supply to a load. That is, the power supply device 100 is in a power supply state. Therefore, the feedback and compensation circuit 140 enables the controller 130 to control the primary side circuit 110 so that the secondary side circuit 120 provides the output voltage VO.

On the other hand, when the sensed voltage value VS is less than the reference value VR, it means that the output current value IO is lower than the current value level. The power supply device 100 stops providing regular power supply to the load. That is, the power supply device 100 is in a low load state. The low load state can be an idle state or a very light load state. Therefore, the feedback and compensation circuit 140 causes the controller 130 to perform a down-frequency operation on the primary side circuit 110 (eg, enter a burst mode). Therefore, the switching power consumption of the primary side circuit 110 can be reduced. In addition, the feedback and compensation circuit 140 also reduces the loop gain LG to reduce the voltage value of the output voltage VO.

It is worth mentioning here that when the sensed voltage value VS is less than the reference value VR, the feedback and compensation circuit 140 reduces the loop gain LG of the power supply device 100 to reduce the voltage value of the output voltage VO. Therefore, the output power can be significantly reduced. In this way, under low load conditions, the power supply device 100 can meet the energy saving requirements of current regulations (such as Lot 7 external power supply EC 278/2009).

Taking this embodiment as an example, the transformer TR has a primary side winding NP and a secondary side winding NS. The primary side circuit 110 is coupled to the primary side winding NP. The secondary circuit 120 is coupled to the secondary winding NS. Primary side circuit 110 includes magnetizing inductor LM and power switch Q1. The magnetizing inductor LM and the primary side winding NP are coupled in parallel to each other. The first terminal of the magnetizing inductor LM receives the input voltage VI. The first terminal of the power switch Q1 is coupled to the second terminal of the magnetizing inductor LM. The second terminal of the power switch Q1 is coupled to the ground terminal GND1. The control terminal of the power switch Q1 is coupled to the controller 130 . The control terminal of the power switch Q1 receives the switching control signal GD provided by the controller 130 . The secondary side circuit 120 includes an output diode DO, an output capacitor CO, and a sensing resistor RS. The anode of the output diode DO is coupled to the first end of the secondary side winding NS. The cathode of the output diode DO serves as the output terminal of the secondary side circuit 120 . The first terminal of the output capacitor CO is coupled to the cathode of the output diode DO. The sensing resistor RS is coupled between the second terminal of the output capacitor CO and the ground terminal GND2. The secondary side circuit 120 converts the output current value IO of the output current flowing through the sensing resistor RS into a sensing voltage value VS.

The power converter CR in this embodiment is a flyback converter with a transformer TR, but the invention is not limited thereto. In some embodiments, power converter CR may be an LLC converter. In some embodiments, the power converter CR may be a non-isolated converter, such as a Buck-Boost converter.

Please refer to FIG. 2 , which is a schematic diagram of a power supply device according to a second embodiment of the present invention. In this embodiment, the power supply device 200 includes a power converter CR, a controller 130 and a feedback and compensation circuit 240 . The power supply device 100 includes a power converter CR, a controller 130 and a feedback and compensation circuit 240 . Power converter CR includes at least a transformer TR, a primary side circuit 110 and a secondary side circuit 120 . The feedback and compensation circuit 240 includes a feedback circuit 241 and a judgment circuit 242 . The feedback circuit 241 provides the feedback signal SFB according to the voltage value of the output voltage VO. The controller 130 adjusts the frequency of the control signal GD according to the feedback signal SFB. Therefore, in the power supply state, the voltage value of the output voltage VO can be stabilized.

The judgment circuit 242 compares the sensed voltage value VS with the reference value VR. When the sensed voltage value VS is greater than or equal to the reference value VR, the judgment circuit 242 will not reduce the loop gain inside the feedback and compensation circuit 240 (as shown in the figure) The loop gain shown in 1 is LG). In addition, the voltage value of the output voltage VO will be stabilized.

On the other hand, when the sensed voltage value VS is less than the reference value VR, the judgment circuit 242 will reduce the loop gain inside the feedback and compensation circuit 240 . Therefore, the output voltage VO will be reduced. In addition, when the sensed voltage value VS is less than the reference value VR, the determination circuit 242 also instructs the controller 130 to perform a down-frequency operation on the primary side circuit 110 .

In this embodiment, the feedback circuit 241 includes a coupling circuit 2411, a voltage regulator 2412, a resistor R1, a voltage dividing resistor RB, and a first compensation circuit 2413. The coupling circuit 2411 is coupled between the controller 130 and the secondary side circuit 120 . The first terminal of the voltage regulator 2412 is coupled to the coupling circuit 2411. The second terminal of the voltage regulator 2412 is coupled to the reference low voltage of the secondary side circuit 120 (for example, the ground terminal GND2). The reference terminal of the voltage regulator 2412 is used to provide a reference value VR. The voltage regulator 2412 causes the coupling circuit 2411 to provide the corresponding feedback signal SFB according to the change in the output voltage VO. Resistor R1 is coupled between the output terminal of secondary side circuit 120 and the reference terminal of voltage regulator 2412 . The voltage dividing resistor RB is coupled between the reference terminal of the voltage regulator 2412 and the second terminal of the voltage regulator 2412 .

In this embodiment, the coupling circuit 2411 may be implemented by an optical coupler (eg, component PC817). The voltage regulator 2412 may be implemented by component TL431. The coupling circuit 2411 includes a light emitting diode and a coupling transistor. The anode of the light-emitting diode is coupled to the output voltage VO. The cathode of the light emitting diode is coupled to the first terminal of the voltage regulator 2412 . The coupling transistor is coupled between the controller 130 and the ground terminal GND1. In this embodiment, the resistor R1 and the voltage dividing resistor RB divide the voltage value of the output voltage VO to obtain the divided voltage value of the output voltage VO. The voltage regulator 2412 receives the divided voltage value and compares the divided voltage value with the reference value VR. When the divided voltage value is different from the reference value VR, the voltage value at the first terminal of the voltage regulator 2412 will change, thereby affecting the light-emitting result of the light-emitting diode. Therefore, the feedback signal SFB generated by the coupling transistor will also change. For example, when the voltage value of the output voltage VO increases, the divided voltage value received by the voltage regulator 2412 will increase. Therefore, the voltage value of the first terminal of the voltage regulator 2412 will be correspondingly reduced. The brightness of the light-emitting diode will increase. Therefore, the current value of the feedback signal SFB provided by the coupling transistor will increase. Then the charging result of the capacitor CB in the image feedback and compensation circuit 240. The controller 130 will reduce the duty cycle of the switching control signal GD according to the charging result of the capacitor CB. Therefore, the voltage value of the output voltage VO will be reduced. Similarly, when the voltage value of the output voltage VO decreases, the controller 130 increases the duty cycle of the switching control signal GD. Therefore, the voltage value of the output voltage VO will be increased. Therefore, in the power supply state, the voltage value of the output voltage VO can be stabilized.

In this embodiment, the first compensation circuit 2413 is coupled between the first terminal of the voltage regulator 2412 and the reference terminal of the voltage regulator 2412 . In this embodiment, the first compensation circuit 2413 and the resistor R1 determine the first pole. In addition, the first compensation circuit 2413 independently determines the second pole and the first zero point. It should be noted that in the power supply state, the first compensation circuit 2413 increases the bandwidth and phase margin.

In this embodiment, the determination circuit 242 determines the sensing voltage value VS. When the sensing voltage value VS is greater than or equal to the reference value VR, the determination circuit 242 will know that the power supply device 200 is in the power supply state. Therefore, in the power supply state, the judgment circuit 242 does not establish the second compensation circuit. On the other hand, when the sensed voltage value VS is less than the reference value VR, the determination circuit 242 will know that the power supply device 200 is in a low load state. Therefore, the judgment circuit 242 establishes the second compensation circuit.

It should be noted that the second compensation circuit and resistor R1 determine the second zero point. The second compensation circuit alone determines the third pole. Therefore, in the low load state, the first compensation circuit 2413 and the second compensation circuit jointly provide 3 poles and 2 zeros. The first compensation circuit 2413 and the second compensation circuit further increase the bandwidth. In addition, the first compensation circuit 2413 and the second compensation circuit can also reduce the loop gain.

Please refer to FIG. 2 , FIG. 3 , FIG. 4 and FIG. 5 at the same time. FIG. 3 is a waveform diagram of a switching control signal and an output voltage according to an embodiment of the present invention. FIG. 4 is a schematic diagram of a loop gain in a power supply state according to an embodiment of the present invention. FIG. 5 is a schematic diagram of the loop gain in a low load state according to an embodiment of the present invention. In this embodiment, the first compensation circuit 2413 includes capacitors C1 and C2 and a resistor R2. The capacitor C1 is coupled between the first terminal of the voltage regulator 2412 and the reference terminal of the voltage regulator 2412 . The capacitor C2 and the resistor R2 are coupled in series between the first terminal of the voltage regulator 2412 and the reference terminal of the voltage regulator 2412 . Based on formula (1), formula (2) and formula (3), the capacitance value of capacitor C1 and the resistance value of resistor R1 determine the first pole f0. The capacitance value of capacitor C2 and the resistance value of resistor R2 determine the first zero point f1. The capacitance value of capacitor C1 and the resistance value of resistor R2 determine the second pole f2.

………….……Formula 1)

………….……Formula (2)

………….……Formula (3)

rR1 is the resistance value of resistor R1. rR2 is the resistance value of resistor R2. cC1 is the capacitance value of capacitor C1. cC2 is the capacitance value of capacitor C2. In this embodiment, the frequency of the first zero point f1 is designed to be greater than the frequency of the first pole f0. The frequency of the second pole f2 is designed to be greater than the frequency of the first zero point f1.

The judgment circuit 242 includes a comparator CP, switches Q2, Q3, an auxiliary resistor R3, and an auxiliary capacitor C3. The non-inverting input terminal of the comparator CP is coupled to the reference terminal of the voltage regulator 2412 . The non-inverting input terminal of the comparator CP receives the sensed voltage value VS. The first terminal of the switch Q2 is coupled to the output terminal of the secondary side circuit 120 . The control terminal of the switch Q2 is coupled to the output terminal of the comparator CP. The auxiliary resistor R3 is coupled between the reference terminal of the voltage regulator 2412 and the second terminal of the switch Q2. The first terminal of the switch Q3 is coupled to the output terminal of the secondary side circuit 120 . The control terminal of switch Q3 is coupled to the output terminal of comparator CP. The auxiliary capacitor C3 is coupled between the reference terminal of the voltage regulator 2412 and the second terminal of the switch Q3.

In this embodiment, in the power supply state ST1, the controller 130 provides a switching control signal GD having an operating frequency range. In order to stabilize the voltage value of the output voltage VO, the switching frequency of the switching control signal GD is adjusted within the operating frequency range. In the power supply state ST1, the output current value IO will be higher. Therefore, the sensing voltage value VS will be greater than or equal to the reference value VR. When the sensed voltage value VS is greater than or equal to the reference value VR, the comparator CP provides a low voltage signal to turn off the switches Q2 and Q3. Therefore, the feedback and compensation circuit 240 provides the loop gain LG1. The voltage value of the output voltage VO will be gained based on the gain value AV1 of the loop gain LG1. The gain value AV1 is substantially equal to the first quotient obtained by dividing the resistance value of the resistor R2 by the resistance value of the resistor R1.

In the low load state ST2, the output current value IO will decrease. Therefore, the sensing voltage value VS will be smaller than the reference value VR. When the sensed voltage value VS is less than the reference value VR, the comparator CP provides a high voltage signal so that the controller 130 performs a frequency reduction operation on the primary side circuit 110 . Therefore, the switching frequency of the switching control signal GD will be reduced. In the low load state ST2, the switching frequency of the switching control signal GD will be lower than the lowest frequency in the operating frequency range.

In addition, the comparator CP also uses the high voltage signal to turn on the switches Q2 and Q3. Therefore, the comparator CP causes the auxiliary resistor R3 and the auxiliary capacitor C3 to be established as the second compensation circuit.

Based on formula (4) and formula (5), the capacitance value of the auxiliary capacitor C3 and the resistance value of the first resistor R1 determine the second zero point f3. The resistance value of the auxiliary resistor R3 and the capacitance value of the auxiliary capacitor C3 determine the third pole f4.

………….……Formula (4)

………….……Formula (5)

cC3 is the capacitance value of auxiliary capacitor C3. rR3 is the resistance value of auxiliary resistor R3. In this embodiment, the frequency of the second zero point f3 is designed to be greater than the frequency of the second pole f2. The frequency of the third pole f4 is designed to be greater than the frequency of the second zero point f3. Therefore, in the low load state ST2, the feedback and compensation circuit 240 provides the loop gain LG2. The gain value AV2 of the loop gain LG2 is lower than the gain value AV1. Therefore, the voltage value of the output voltage VO will be reduced based on the gain value AV2 of the loop gain LG2. In this embodiment, the gain value AV2 is substantially equal to the second quotient obtained by dividing the capacitance value of the auxiliary capacitor C3 by the capacitance value of the capacitor C2.

For example, the power supply device 200 is applied to a notebook computer, and in the power supply state ST1, the voltage value of the output voltage VO is approximately 19 volts. The output current value IO is approximately 4.74 amps. In the low load state ST2, the output current value IO is lower than 1 amp, so that the sensing voltage value VS associated with the output current value IO is smaller than the reference value VR. The controller 130 performs a frequency down operation on the primary side circuit 110 . Therefore, the switching power consumption of the primary side circuit 110 can be reduced. Additionally, a second compensation circuit is built to reduce the loop gain. The voltage value of the output voltage VO is reduced by 10 volts. Therefore, the output power of the power supply device 200 can be greatly reduced. When the power supply device 200 returns to the power supply state ST1, the sensing voltage value VS will be greater than or equal to the reference value VR. Therefore, the controller 130 stops the frequency down operation of the primary side circuit 110 . Furthermore, the second compensation circuit will not be established. The voltage value of the output voltage VO will return to 19 volts.

In summary, when the sensed voltage value is less than the reference value, the loop gain of the power supply device is reduced and the voltage value of the output voltage is reduced. Therefore, the output power can be significantly reduced. In this way, under low load conditions, the power supply device can meet the energy saving requirements of current regulations.

Although the present invention has been disclosed above through embodiments, they are not intended to limit the present invention. Anyone with ordinary knowledge in the technical field may make some modifications and modifications without departing from the spirit and scope of the present invention. Therefore, The protection scope of the present invention shall be determined by the appended patent application scope.

100, 200: Power supply device

110: Primary side circuit

120:Secondary side circuit

130:Controller

140, 240: Feedback and compensation circuit

241:Feedback circuit

2411: Coupling circuit

2412: Voltage regulator

2413: First compensation circuit

242:Judgement circuit

AV1, AV2: gain value

C1, C2, CB: capacitor

CO: output capacitor

C3: Auxiliary capacitor

CP: Comparator

CR: power converter

DO: output diode

f0: first pole

f1: first zero point

f2: second pole

f3: second zero point

f4: third pole

GD: switching control signal

GND1, GND2: ground terminal

IO: output current value

LG, LG1, LG2: loop gain

LM: Magnetizing inductor

NP: primary side winding

NS: secondary side winding

Q1: Power switch

Q2, Q3: switch

R1, R2: resistor

R3: Auxiliary resistor

RB: voltage dividing resistor

RS: sensing resistor

SFB: feedback signal

ST1: power supply status

ST2: low load state

t: time

TR: Transformer

VI: input voltage

VO: output voltage

VS: sensing voltage value

VR: reference value

FIG. 1 is a schematic diagram of a power supply device according to a first embodiment of the present invention. FIG. 2 is a schematic diagram of a power supply device according to a second embodiment of the present invention. FIG. 3 is a waveform diagram of a switching control signal and an output voltage according to an embodiment of the present invention. FIG. 4 is a schematic diagram of a loop gain in a power supply state according to an embodiment of the present invention. FIG. 5 is a schematic diagram of the loop gain in a low load state according to an embodiment of the present invention.

100:Power supply device

110: Primary side circuit

120:Secondary side circuit

130:Controller

140: Feedback and compensation circuit

CO: output capacitor

CR: power converter

DO: output diode

GD: switching control signal

GND1, GND2: ground terminal

IO: output current value

LG: loop gain

LM: Magnetizing inductor

NP: primary side winding

NS: secondary side winding

Q1: Power switch

RS: sensing resistor

TR: Transformer

VI: input voltage

VO: output voltage

VS: sensing voltage value

VR: reference value

Claims (10)

A power supply device includes: a power converter, including a primary side circuit and a primary side circuit, wherein the secondary side circuit generates a sensing voltage value based on an output current value; a controller coupled to the primary side circuit a side circuit configured to utilize a control signal to control the primary side circuit; and a feedback and compensation circuit coupled to the secondary side circuit and the controller configured to: in the feedback and compensation circuit Provide a loop gain, wherein when the sensed voltage value is greater than or equal to a reference value, the feedback and compensation circuit enables the controller to control the primary side circuit, thereby causing the secondary side circuit to output an output voltage, wherein The output voltage is related to the loop gain, and when the sensed voltage value is less than the reference value: the feedback and compensation circuit causes the controller to perform a frequency reduction operation on the primary side circuit, and the feedback and compensation circuit The circuit increases the zeros and poles of the loop gain to reduce the gain value of the loop gain, so that the voltage value of the output voltage is reduced according to the loop gain. The power supply device of claim 1, wherein the feedback and compensation circuit includes: a judgment circuit configured to compare the sensed voltage value with the reference value. When the sensed voltage value is less than the reference value When , reduce the loop gain and indicate The controller performs the frequency reduction operation on the primary side circuit. The power supply device of claim 2, wherein the feedback and compensation circuit further includes: a feedback circuit configured to provide a feedback signal according to the voltage value of the output voltage in a power supply state, wherein the The controller adjusts the frequency of the control signal according to the feedback signal to stabilize the voltage value of the output voltage. The power supply device of claim 3, wherein the feedback circuit includes: a coupling circuit coupled between the controller and the secondary side circuit; a voltage regulator, the first terminal of the voltage regulator Coupled to the coupling circuit, the second terminal of the voltage regulator is coupled to the reference low voltage of the secondary side circuit, and the reference terminal of the voltage regulator is used to provide the reference value, wherein the voltage regulator is based on the output The change in voltage causes the coupling circuit to provide the feedback signal; a first resistor is coupled between the output terminal of the secondary side circuit and the reference terminal of the voltage regulator; a voltage dividing resistor is coupled to between the reference terminal of the voltage regulator and the second terminal of the voltage regulator; and a first compensation circuit coupled between the first terminal of the voltage regulator and the reference terminal of the voltage regulator, the third a compensation circuit and the first resistor determine a first pole of the loop gain, and The first compensation circuit alone determines a second pole of the loop gain and a first zero point of the loop gain. The power supply device of claim 4, wherein the first compensation circuit includes: a first capacitor coupled between the first terminal of the voltage regulator and the reference terminal of the voltage regulator; a second resistor and a second capacitor coupled in series with the second resistor between the first terminal of the voltage regulator and the reference terminal of the voltage regulator. The power supply device of claim 5, wherein: the capacitance value of the first capacitor and the resistance value of the first resistor determine the first pole, and the capacitance value of the first capacitor and the resistance value of the second resistor determine the first pole. The capacitance value of the second capacitor and the resistance value of the second resistor determine the first zero point. The power supply device of claim 4, wherein: when the sensed voltage value is less than the reference value, the judgment circuit establishes a second compensation circuit, and the second compensation circuit and the first resistor determine the loop gain. a second zero point, and the second compensation circuit alone determines a third pole of the loop gain. The power supply device of claim 7, wherein the judgment circuit includes: a comparator, the non-inverting input terminal of the comparator is coupled to the reference terminal of the voltage regulator, the non-inverting input terminal of the comparator Receive the sensed voltage value; a first switch, the first terminal of the first switch is coupled to the output terminal of the secondary side circuit, and the control terminal of the first switch is coupled to the output terminal of the comparator; a An auxiliary resistor, coupled between the reference terminal of the voltage regulator and the second terminal of the first switch; a second switch, the first terminal of the second switch is coupled to the output terminal of the secondary side circuit , the control terminal of the second switch is coupled to the output terminal of the comparator; and an auxiliary capacitor is coupled between the reference terminal of the voltage regulator and the second terminal of the second switch. The power supply device of claim 8, wherein when the sensed voltage value is less than the reference value, the comparator turns on the first switch and the second switch, so that the auxiliary resistor and the auxiliary capacitor are established as the second compensation circuit. The power supply device of claim 8, wherein: the capacitance value of the auxiliary capacitor and the resistance value of the first resistor determine the second zero point, and the resistance value of the auxiliary resistor and the capacitance value of the auxiliary capacitor Determine this third pole.

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