TW201513539A - Power control device for dynamically adjusting frequency - Google Patents

Abstract

A power control device for dynamically adjusting frequency includes a transformer unit, a controller, a loading feedback unit, and a switching transistor. The transformer unit includes a primary winding, a secondary winding and an auxiliary winding. The primary winding is connected to an input power unit. The secondary winding is connected to a loading unit to generate an output power by inducing the primary winding. The auxiliary winding generates a power sensing signal by inducing the primary winding. The loading feedback unit generates a loading feedback signal. The controller determines the level of loading based on the loading feedback signal and further detects the valleys of the power sensing signal so as to change the switching signal at the optimal valley. Therefore, this invention can dynamically change the frequency of the switching signal, so that, when the loading is getting lighter, the frequency of the switching signal is getting lower thereby reducing the switching loss and improving the overall power conversion efficiency.

Description

Dynamic frequency adjustment power control device

The invention relates to a dynamic frequency adjustment power control device, in particular, using a load feedback signal to determine the load level and detecting the bottom of the power sensing signal, and changing the switching signal of controlling the switching transistor conduction according to the load level at the optimal valley bottom. .

Because of the different power requirements of various electronic products, such as direct current, alternating current, or different voltages, currents, and power, power supply providers must continuously develop appropriate power converters to meet actual needs. For example, electric motors typically require 12V DC drive, so the power converter needs to convert 110V mains to 12V DC or convert lower voltage battery power to 12V. Integrated circuits (ICs) or electronic components typically use 5V, 3.3V, 2.5V, or even 1.8V DC, so the power converter needs to be able to convert the mains to a suitable low voltage source. In addition, for some high-voltage applications, such as liquid-through panels, power converters need to provide high-voltage AC power to supply the lamp to light. This power converter is generally called an inverter and can supply 12V DC from the battery. Convert to AC power of 110V or higher.

In the conventional technology, the switching power converter is a generally common power converter, which has the advantages of simple architecture, low cost, and large voltage modulation range, especially by zero voltage and/or zero current switching. Reduce the switching loss (switching loss) of switching components (usually power transistors) to improve power conversion efficiency.

Specifically, the switching power converter mainly generates pulse width modulation. The (PWM) signal is used as a driving signal to drive a switching transistor that controls the on-current of the coil winding on the transformer to achieve the purpose of changing the voltage and/or current of the output power supply. Due to the inductive effects from the coil windings on the circuit, as well as the effects of peripheral capacitors, electronic components, loads or parasitic capacitances, attenuating oscillations occur due to inductive-inductive coupling over a period of time after the switching transistor is turned off. In order to reduce the switching loss, it is often necessary to switch the switching transistor at the bottom of the oscillation, that is, to switch the valley switching of the switching transistor, wherein the operation of the valley switching is generally a fixed valley switching. That is, when the preset number of fixed valleys is preset, the switching transistor is turned on.

However, the disadvantage of the fixed trough number switching in the prior art is that the lower the load, the higher the frequency of the switching signal, and the heavier the load, the lower the frequency of the switching signal, resulting in a significant reduction in overall power conversion efficiency. That is, the optimal frequency of the switching signal cannot be dynamically adjusted according to the degree of load.

Therefore, there is a need for a dynamic frequency adjustment power control device that utilizes specific control principles to determine the number of valleys that change the switching signal. The lighter the load, the lower the frequency of the switching signal, which can effectively reduce switching losses and improve overall power conversion. Efficiency, to solve the problems of the above-mentioned conventional technology.

The main object of the present invention is to provide a dynamic frequency adjustment power control device electrically connected to an input power supply unit and a load unit for converting an input power of an input power supply unit into an output power supply for supplying power to a load unit, and a dynamic frequency adjustment power supply. The control device mainly comprises a transformer unit, a controller, a load feedback unit and a switching transistor, and the transformer unit comprises a primary side coil, a secondary side coil and an auxiliary coil, wherein the primary side coil of the transformer unit is connected to the input power unit, and the second The side coil is connected to the load unit, and the output power is generated by sensing the primary side coil. The auxiliary coil generates a power sensing signal corresponding to the output power source by inducing the primary side coil, and the load feedback unit is coupled to the secondary side coil and the load unit for A load feedback signal corresponding to the output power source is generated. The controller receives the power sensing signal and the load feedback signal, and generates a switching signal according to a preset control principle, and the switching electric crystal system connected to the controller and the primary side coil receives the switching signal to control the conduction current of the primary side coil, In turn, the purpose of power conversion is achieved.

The above control principle is mainly used to control the switching frequency of the switching signal. Specifically, the control principle includes determining the load level according to the load feedback signal, detecting the bottom of the power sensing signal, and changing the switching signal of the control switching transistor at the optimal valley according to the load level, especially in the When the load is lighter, the number of switching valleys is increased to lower the frequency of the switching signal, wherein the switching time of the switching transistor or the high level timing of the switching signal is controlled by the load feedback signal.

Therefore, the dynamic frequency adjustment power control device of the present invention can dynamically change the frequency of the switching signal according to the degree of load, so that the lighter the load, the lower the frequency of the switching signal, and the heavier the load, the higher the frequency of the switching signal, thereby reducing the frequency. Switch losses and improve overall power conversion efficiency.

10‧‧‧Input power unit

12‧‧‧Load unit

20‧‧‧Transformer unit

21‧‧‧One-side coil

22‧‧‧second side coil

23‧‧‧Auxiliary coil

30‧‧‧ Controller

40‧‧‧Load feedback unit

50‧‧‧Switching transistor

A, B, C, D‧‧‧ arrows

PWM‧‧‧ switching signal

R1, R2‧‧‧ voltage divider resistor

TD‧‧‧Optocoupler

VFB‧‧‧ load feedback signal

Vaux‧‧‧ power sensing signal

The first figure shows a schematic diagram of a dynamic frequency adjustment power control device according to an embodiment of the present invention.

The second figure shows an operational waveform diagram of the dynamic frequency adjustment power supply control device of the embodiment of the present invention.

The third figure shows another operational waveform diagram of the dynamic frequency adjustment power supply control device of the embodiment of the present invention.

The fourth figure shows a schematic diagram of the dynamic frequency adjustment power control device of the embodiment of the present invention generating a load feedback signal in a primary side feedback manner.

The fifth figure shows a schematic diagram of a dynamic frequency adjustment power supply control device generating a load feedback signal in a secondary side feedback manner according to an embodiment of the present invention.

The embodiments of the present invention are described in more detail below with reference to the drawings and the component symbols. Explain that the person skilled in the art can implement it after studying this manual.

Referring to the first figure, a schematic diagram of a dynamic frequency adjustment power control device according to an embodiment of the present invention. As shown in the first figure, the dynamic frequency adjustment power control device of the embodiment of the present invention is electrically connected to the input power unit 10 and the load unit 12, and the dynamic frequency adjustment power control device includes the transformer unit 20, the controller 30, and the load feedback unit. 40 and a switching transistor 50 for converting the input power of the input power unit 10 into an output power source for supplying power to the load unit 12, wherein the voltage and/or current of the output power source is different from the voltage and/or current of the input power source.

The controller 30 can be implemented using a microcontroller (MCU).

The transformer unit 20 of the present invention includes a primary side coil 21, a secondary side coil 22, and an auxiliary coil 23, and is wound around individual iron cores (not shown) to improve electrical effects, wherein the primary side coil 21 of the transformer unit 20 is connected. The power supply unit 10 is input, and the secondary side coil 22 is coupled to the load unit 12 to generate an output power by inducing the primary side coil 21, and the auxiliary coil 23 generates a power supply sensing signal Vaux by sensing the primary side coil 21.

The load feedback unit 40 connects the secondary side coil 22 and the load unit 12 for generating a load feedback signal VFB corresponding to the output power.

The controller 30 receives the power sensing signal Vaux and the load feedback signal VFB, and generates a switching signal PWM according to a preset control principle, and the switching transistor 50 connected to the controller 30 and the primary side coil 21 receives the switching signal PWM. The on-current and/or voltage of the primary side coil 21 is controlled to further control the current and/or voltage of the secondary side coil 22 to generate a desired output power source for the purpose of power conversion.

The above control principle is mainly used to control the switching frequency of the switching signal PWM. Referring to the second figure, an operation waveform diagram of the dynamic frequency adjustment power supply control device according to the embodiment of the present invention, wherein the switching transistor 50 turns off the conduction path of the primary side coil 21 according to the switching signal PWM, such as a low level switching signal PWM, once After the inductor current of the side coil 21 drops to zero, one The voltage of the secondary side coil 21 oscillates, so that the power supply sensing signal Vaux also oscillates in synchronization. Therefore, the power supply sensing signal Vaux will gradually converge through a plurality of valleys. When the power supply sensing signal Vaux is at the bottom, if the switching signal PWM is switched from the low level to the high level to turn on the conduction path of the primary side coil 21, the switching loss is minimized. Therefore, the main purpose of the control principle in the present invention is to change the level of the switching signal PWM when the power supply sensing signal Vaux is the optimum valley.

Specifically, the control principle includes: determining a load level according to the load feedback signal VFB; detecting a valley of the power sensing signal Vaux; and selecting an optimal valley number according to the load level to change the switching signal PWM of the control switching transistor 50. For example, switching from a low level to a high level, thereby turning on the switching transistor 50. The optimal valley bottom is selected by increasing the number of switching valleys when the load is lighter, that is, when the load is lighter, the switching signal PWM is changed later, thereby reducing the frequency of the switching signal, wherein switching the on-time of the transistor 50 or switching The high level timing of the signal is controlled by the load feedback signal VFB.

In order to detect the valley position of the power sensing signal Vaux, the power sensing signal Vaux of the previous time and the previous time can be continuously compared to determine the time point when the power sensing signal Vaux is the local minimum value, and can be predicted accordingly. The time at which the bottom of the valley occurs occurs because the LC oscillation frequency causing the power supply sensing signal Vaux to oscillate is fixed.

In order to further illustrate the features of the present invention, please refer to the second and third figures, which show two different operational waveform diagrams of the dynamic frequency adjustment power supply control device according to the embodiment of the present invention, wherein the high level of the switching signal PWM is maintained for a fixed time. As shown in the second figure, the switching signal PWM is switched from the low bit to the high level, which is preset at the seventh bottom of the power sensing signal Vaux, and the seventh bottom of the power sensing signal Vaux and the switching are indicated by arrows A and B, respectively. Signal PWM switching. In addition, as shown in the third figure, the switching signal PWM is switched from the low bit to the high level, which is preset to the third bottom of the power sensing signal Vaux. The switching of the third valley of the power supply sensing signal Vaux and the switching signal PWM is not indicated by arrows C and D.

It is apparent from the second and third figures that the switching signal PWM of the second figure has a lower frequency, and the switching signal PWM of the third figure has a higher frequency because the second picture switching signal PWM is changed. The number of valley bottoms is greater than the third graph, that is, the low level timing of the second graph switching signal PWM is long, so that the period of the switching signal PWM is long, resulting in a lower frequency.

The operation method for selecting the best valley bottom in detail is explained below.

First, the degree of load represented by the load feedback signal VFB is determined mainly by using the preset first comparison value CMP_H, the second comparison value COMP_M, the third comparison value COMP_ML, and the fourth comparison value COMP_L. Specifically, the first comparison value CMP_H is greater than the second comparison value COMP_M, the second comparison value COMP_M is greater than the third comparison value COMP_ML, and the third comparison value COMP_ML is greater than the fourth comparison value COMP_L.

If the load feedback signal VFB is greater than or equal to the first comparison value CMP_H, indicating that the load level is a heavy load, the number of valleys is set to 0, that is, the continuous conduction mode (CCM) is performed.

If the load feedback signal VFB is smaller than the first comparison value CMP_H, the number of valleys is set to at least 1, such as 3, depending on actual needs, to enter the discontinuous conduction mode (DCM). Therefore, the switching signal PWM changes the level of the third valley of the power sensing signal Vaux, and switches from the low level to the high level, thereby implementing the discontinuous conduction mode (DCM). Thereafter, if the load feedback signal VFB is greater than the second comparison value COMP_M and less than the first comparison value CMP_H, the number of valleys is set to the previously set number of valleys minus one for changing the switching signal PWM until the number of valleys is=1.

If the load feedback signal VFB is greater than the third comparison value COMP_ML and less than the second comparison value COMP_M, the set number of valleys is maintained unchanged. If the load feedback signal VFB is greater than the fourth comparison value COMP_L and less than the third comparison value COMP_ML, the number of valleys is set to the previously set bottom The number is incremented by one until the set bottom is the maximum acceptable for the system, such as 20.

If the load feedback signal VFB is smaller than the fourth comparison value COMP_L, indicating that the load level is extremely light load, the number of valleys is set to the maximum value and enters the burst mode.

Therefore, the present invention can provide a lower frequency switching signal PWM at a low load and increase the frequency of the switching signal PWM at a heavy load.

In addition, the controller 30 can have a function of setting a hysteresis voltage to the first comparison value CMP_H, the second comparison value COMP_M, the third comparison value COMP_ML, and the fourth comparison value COMP_L, thereby generating a hysteresis effect, which can prevent the switching signal PWM from being high. When the low level is switched, it will have an unstable effect on the overall system operation.

For a specific example of the load feedback unit 40 for generating the load feedback signal VFB in the present invention, reference may be made to the fourth and fifth figures, which respectively show the dynamic frequency adjustment power supply control using the primary side and secondary side feedback modes to implement the embodiment of the present invention. Device.

As shown in the fourth figure, the load feedback unit 40 mainly includes serially connected bistatic resistors R1 and R2, is connected to the auxiliary coil 23, and generates a load feedback signal VFB at the series connection point of the voltage dividing resistors R1 and R2. In addition, as shown in the fifth figure, the load feedback unit 40 mainly includes an optical coupler TD (also referred to as an opto-isolator, an optocoupler) for generating a sensing current IS corresponding to the load unit 12 by optical coupling. The required load feedback signal VFB, wherein the optical coupler TD is composed of a light-emitting element and a light-receiving element.

It is to be noted that the third and fourth figures are merely exemplary embodiments for illustrating the features of the present invention, and are not intended to limit the scope of the present invention, that is, the input power unit 10, the load unit 12, and the transformer unit of the present invention. 20. The controller 30, the load feedback unit 40, and the switching transistor 50 can be used to provide other circuit components of the same electrical function.

In summary, the invention is characterized in that the cutting can be dynamically changed according to the degree of load. When the frequency of the signal is changed, the lower the load, the lower the frequency of the switching signal, and the heavier the load, the higher the frequency of the switching signal, thereby reducing the switching loss and improving the overall power conversion efficiency.

The above is only a preferred embodiment for explaining the present invention, and is not intended to limit the present invention in any way, and any modifications or alterations to the present invention made in the spirit of the same invention. All should still be included in the scope of the intention of the present invention.

10‧‧‧Input power unit

12‧‧‧Load unit

20‧‧‧Transformer unit

21‧‧‧One-side coil

22‧‧‧second side coil

23‧‧‧Auxiliary coil

30‧‧‧ Controller

40‧‧‧Load feedback unit

50‧‧‧Switching transistor

PWM‧‧‧ switching signal

VFB‧‧‧ load feedback signal

Vaux‧‧‧ power sensing signal

Claims (6)

A dynamic frequency adjustment power control device is electrically connected to an input power supply unit and a load unit for converting an input power of the input power supply unit into an output power supply to the load unit, and the dynamic frequency adjustment power supply control The device includes: a transformer unit including a primary side coil, a secondary side coil, and an auxiliary coil, wherein the primary side coil is coupled to the input power unit, and the secondary side coil is coupled to the load unit and senses the primary side coil Generating the output power, and the auxiliary coil generates a power sensing signal by sensing the primary side coil; a load feedback unit is coupled to the secondary side coil and the load unit for generating a corresponding power source a load feedback signal; a controller receiving the power sensing signal and the load feedback signal, and generating a switching signal according to a preset control principle; and a switching transistor connecting the controller and the primary side a coil and receiving the switching signal to control an on current and/or voltage of the primary side coil And controlling the current and/or voltage of the secondary side coil, wherein the control principle comprises: determining a load level according to the load feedback signal; detecting a bottom of the power sensing signal; and selecting the most according to the load level A good number of valleys is used to change the switching signal that controls the switching transistor. According to the dynamic frequency adjustment power supply control device of claim 1, wherein the number of valleys of the control principle is selected and changed according to the following method: using a preset first comparison value, a second comparison value, and a a third comparison value and a fourth comparison value to compare the load feedback signal, thereby determining a load level represented by the load feedback signal, and the first comparison value is greater than the second comparison value, the second comparison value being greater than the first Comparing a value, wherein the third comparison value is greater than the fourth comparison value; if the load feedback signal is greater than or equal to the first comparison value, setting the number of valleys to 0 to enter a continuous conduction mode (CCM), and if The load feedback signal is smaller than the first a comparison value, the number of valleys is set to at least 1 to enter a discontinuous conduction mode (DCM); thereafter, if the load feedback signal is greater than the second comparison value and less than the first comparison value, the number of valleys is set to The number of valleys previously set is decreased by 1 until the number of valleys is=1; if the load feedback signal is greater than the third comparison value and less than the second comparison value, the set number of valleys is maintained unchanged; if the load feedback signal is greater than The fourth comparison value is less than the third comparison value, and the number of the fixed bottom is set to 1 for the previously set valley number until the set bottom number is an acceptable maximum value; and if the load feedback signal is at the first For four comparison values, the number of valleys is set to a maximum value to enter a burst mode. The dynamic frequency adjustment power supply control device according to claim 1, wherein the controller is implemented by using a microcontroller (MCU). The dynamic frequency adjustment power supply control device according to claim 1, wherein the controller has a set hysteresis voltage for the first comparison value, the second comparison value, the third comparison value, and the fourth comparison value. The function to produce a hysteresis effect. The dynamic frequency adjustment power supply control device according to claim 1, wherein the load feedback unit is implemented on a primary side, and the load feedback unit includes a serially connected voltage divider resistor connected to the auxiliary coil. And generating the load feedback signal at the series connection point of the bipartite resistor. The dynamic frequency adjustment power supply control device according to claim 1, wherein the load feedback unit is implemented in a secondary side feedback manner, and the load feedback unit includes an optical coupler for corresponding to the load. A sensing current of the unit generates the load feedback signal by optical coupling, and the optical coupler is composed of a light emitting element and a light receiving element. .