CN219068080U

CN219068080U - Wide-range voltage-adjustable power supply circuit

Info

Publication number: CN219068080U
Application number: CN202223295744.XU
Authority: CN
Inventors: 龙启强; 战宏光; 黄杉
Original assignee: Thermo Fisher Scientific Shanghai Instruments Co Ltd
Current assignee: Thermo Fisher Scientific Shanghai Instruments Co Ltd
Priority date: 2022-12-08
Filing date: 2022-12-08
Publication date: 2023-05-23
Anticipated expiration: 2032-12-08

Abstract

The utility model provides a wide-range voltage-adjustable power supply circuit, which comprises: a first AC-DC conversion module configured to convert an AC input power into a DC output power based on a control signal; a voltage detection unit configured to sample an output voltage of the first AC-DC conversion module; a controllable current source. The controllable current source includes: a constant current source coupled to an output side of the first AC-DC conversion module; and a first comparison module coupled to the constant current source and the voltage detection unit and configured to enable the constant current source in response to the sampled voltage of the voltage detection unit decreasing below a first threshold.

Description

Wide-range voltage-adjustable power supply circuit

Technical Field

The utility model relates to a power supply technology, in particular to a wide-range voltage-adjustable power supply circuit.

Background

Some electronic devices operate over a wide range of voltages. The load voltage of such devices may vary widely, for example 20V-3500V. For such devices, a dedicated power supply circuit is required to convert 220V/50Hz ac power, for example, picked up from the grid, to dc power with the required voltage. Since the voltage required by the load may change in real time as the operating state of the electronic device changes, the output voltage of the power supply circuit also needs to change accordingly.

One implementation of a wide range power supply circuit is to first convert ac power to dc power at a fixed voltage using a PFC (Power Factor Correction: power factor correction) circuit and then further convert the dc power at the fixed voltage to dc power at a desired voltage using a dc converter.

A typical dc converter uses a rectifier bridge formed of power switching devices to boost and buck dc power. The gate of the power switching device receives a PWM (Pulse Width Modulation: pulse width modulated) signal as a gating signal. By controlling the duty cycle of the PWM signal, the output voltage of the dc converter may be regulated.

However, for a wide range power supply circuit, the duty cycle of the PWM signal may be very low when the load voltage is low. After the controller outputs a number of PWM pulses, it is necessary to wait until the output voltage drops to a set operating value. This results in a larger ripple in the output circuit. Ripple can lead to output instability, especially in the case of low voltage loads.

Disclosure of Invention

The present utility model provides a wide range power supply circuit that can provide stable voltage output even under low voltage loads.

One aspect of the present utility model provides a wide range voltage tunable power circuit, which may include: a first AC-DC conversion module configured to convert an AC input power into a DC output power based on a control signal; a voltage detection unit configured to sample an output voltage of the first AC-DC conversion module; a controllable current source. The controllable current source may include: a constant current source coupled to an output side of the first AC-DC conversion module; and a first comparison module coupled to the constant current source and the voltage detection unit and configured to enable the constant current source in response to the sampled voltage of the voltage detection unit decreasing below a first threshold.

According to this embodiment, when the power supply voltage is in the low-voltage output state, the constant current source can be coupled to the output side to increase the load impedance of the output side, whereby the ripple in the circuit can be suppressed, and the stability at the time of low-voltage load can be improved.

In an alternative embodiment, the first comparison module may be further configured to disable the constant current source in response to the sampling voltage rising above a second threshold, wherein the second threshold is higher than the first threshold.

According to this embodiment, when the output voltage of the power supply circuit rises to a point where an additional load is no longer required to stabilize the voltage, the constant current source can be disabled to avoid the generation of additional heat and loss. Further, by setting the buffer between the second threshold value and the first threshold value, the constant current source can be prevented from being frequently enabled or disabled.

In an alternative embodiment, the constant current source may be disabled before the sampling voltage decreases from above the second threshold to below the first threshold.

In an alternative embodiment, the first threshold may be set such that the output voltage of the wide-range adjustable power supply circuit is within a predetermined amplitude range when the constant current source is enabled.

According to this embodiment, the first threshold value for enabling the constant current source can be determined according to the required voltage stability, and thus the timing of enabling the constant current source can be determined according to the required voltage stability, avoiding enabling the constant current source too early or too late.

In an alternative embodiment, the second threshold may be set such that the operating temperature of the wide range adjustable power supply circuit is below a predetermined upper operating temperature limit when the constant current source is enabled.

According to this embodiment, the second threshold for disabling the constant current source can be determined from the maximum operating temperature, so that the circuit can operate within the safe temperature interval.

In an alternative embodiment, the first controller may be further included, coupled to the voltage detection unit and the first AC-DC conversion module, and configured to provide a control signal to the first AC-DC conversion module based on the sampled voltage. The first AC-DC conversion module may include: a PFC circuit configured to convert ac input power to dc power; a BUCK circuit coupled to the first controller and configured to receive the dc power and step down the dc power based on a control signal from the first controller; and a BUCK/BOOST circuit coupled to the BUCK circuit and the first controller and configured to voltage convert the stepped down dc power as a dc output power based on the control signal.

According to this embodiment, the controller provides control signals to both the BUCK circuit and the BUCK/BOOST circuit. When the load voltage is reduced, the control signal of the controller can reduce the output voltage of the BUCK circuit, so that the reduction amplitude of the output voltage of the BUCK/BOOST circuit can be relieved.

In an alternative embodiment, the BUCK/BOOST circuit may be a flyback dc conversion circuit including a transformer, the primary side of the transformer including a flyback controller, and the secondary side may include: at least one loop consisting of a freewheeling diode and a first RC filter; and a second comparing module, wherein the output voltage of the secondary side is fed back to the first input end of the second comparing module, the control signal is input to the second input end of the second comparing module via a second RC filter, and the output end of the second comparing module is coupled to the feedback end of the flyback controller via a photoelectric coupler.

According to this embodiment, the control signal indicative of the target output voltage can be rectified by the second RC filter into a direct current signal which is provided to the second comparison module. The second comparison module is capable of comparing the target output voltage indicated by the control signal with the feedback voltage to control operation of the optocoupler, thereby controlling whether the flyback controller is started.

In an alternative embodiment, a second controller may be further included, the second controller communicatively coupled with the first controller and configured to: an interrupt instruction is sent to the first controller in response to a user input indicating to stop or interrupt operation of the power supply circuit. The control signal may be a PWM signal. The first controller may be further configured to: in response to receiving the interrupt instruction, adjusting the duty cycle of the control signal to 0 to cause the power supply circuit to enter a discharge mode; and during the discharge mode, the sampling voltage is transmitted to the second controller in real time or periodically.

According to this embodiment, the first controller is capable of causing the power circuit to enter a discharge mode when the operator interrupts or shuts down the device. The second controller is capable of determining a remaining voltage of the power supply circuit based on the sampling circuit acquired from the first controller during the discharge mode.

In an alternative embodiment, the second controller may be further configured to: an instruction to stop the discharge mode is sent to the first controller in response to the received sampling voltage being below a third threshold. The first controller may be further configured to: in response to receiving an instruction to stop the discharge mode, the transmission of the sampling voltage to the second controller is stopped.

According to this embodiment, the discharge mode can be stopped after the output voltage of the power supply circuit is reduced to a safe level.

In an alternative embodiment, the first controller may be coupled to a constant current source and further configured to: enabling a constant current source during a discharge mode; and disabling the constant current source in response to ending the discharge mode.

According to this embodiment, the constant current source can be enabled during the discharge mode to accelerate the release of the circuit energy.

Drawings

FIG. 1 illustrates a block diagram of an example wide range voltage tunable power circuit 10A in accordance with the techniques of this disclosure;

FIG. 2 illustrates a circuit diagram of an example topology of a wide range voltage tunable power supply circuit 10A in accordance with the techniques of the present disclosure;

FIG. 3 illustrates a circuit diagram of an example topology of another example wide range voltage tunable power circuit 10B in accordance with the techniques of this disclosure; and is also provided with

Fig. 4 illustrates an example shutdown process 400 of the example wide range voltage tunable power circuit 10B shown in fig. 3 in accordance with the techniques of this disclosure.

Detailed Description

In the following description, numerous specific details are set forth. It may be evident, however, that the embodiments of the present utility model may be practiced without these specific details. In other instances, well-known circuits, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.

References in the specification to "one embodiment," "an example embodiment," etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Furthermore, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to effect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

For the purposes of this disclosure, the phrase "a and/or B" means (a), (B), or (a and B). For the purposes of this disclosure, the phrase "A, B, and/or C" means (a), (B), (C), (a and B), (a and C), (B and C), or (A, B and C).

In the drawings, a particular arrangement or order of illustrative elements is shown for ease of description. However, those skilled in the art will appreciate that the particular ordering or arrangement of illustrative elements in the figures is not intended to imply that a particular order or sequence of processing, or separation of processes, is required. Furthermore, the inclusion of schematic elements in the figures is not meant to imply that such elements are required in all embodiments, or that features represented by such elements may not be included in or combined with other elements in some embodiments.

SUMMARY

A typical dc converter has a feedback mechanism. The dc conversion controller controls the dc converter to output a desired voltage based on the fed-back output voltage and puts the dc converter in a proper operation state, for example, by controlling the duty ratio, the switching frequency, etc. of the PWM signal. For a wide range power supply circuit, when the output voltage is low, it is difficult for the dc conversion controller to control the dc converter to suppress ripple. For example, for an output voltage of 20V, the desired output voltage amplitude range is, for example, between 19.1V and 20.9V. The presence of ripple may cause the actual amplitude of the output voltage to exceed 19.1V-20.9V, resulting in reduced stability at low load voltages.

To ensure stability of a wide range power supply circuit at low load voltages, the present disclosure couples a constant current source at the output side of the dc converter. The constant current source may be enabled when the output voltage is low. The constant current source may be constituted by a high voltage tolerant MOSFET, a transistor, and a resistor, and may be regarded as a load. The current flowing into the constant current source is kept constant according to the set value, irrespective of the magnitude of the voltage across the constant current source. After the constant current source is coupled to the output side, the load impedance is increased, so that the fluctuation range of the voltage can be reduced, and the voltage stability during low-voltage output can be improved.

Example 1

Fig. 1 illustrates a block diagram of an example wide range voltage tunable power circuit 10A in accordance with the techniques of this disclosure. The power supply circuit 10A of the present embodiment includes an AC-DC conversion module 1 (also referred to herein as a "first AC-DC conversion module"), a controller 2 (also referred to herein as a "first controller"), a voltage detection unit 3, and a controllable current source 4.

The AC-DC conversion module 1 takes alternating current power as AC input from, for example, a power grid. The AC-DC conversion module 1 performs power conversion based on a control signal from the controller 2, and outputs direct current power. The control signal indicates a target output voltage.

The voltage detection unit 3 samples the output voltage Vout of the AC-DC conversion module 1 and feeds back the sampled voltage to the controller 2. The sampling voltage may be obtained by dividing the output voltage Vout.

The controller 2 generates a control signal for the AC-DC conversion module 1 based on the set target output voltage. The AC-DC conversion module 1 may comprise a rectifier bridge consisting of several power switching devices. The controller 2 may provide a control signal indicating the target output voltage to the driver of the AC-DC conversion module 1. The driver of the AC-DC conversion module 1 supplies a gate signal to the gates of the respective power switching devices based on the control signal to realize control of the output voltage. The AC-DC conversion module 1 may be constituted by an AC-DC converter, or may be constituted by an AC-DC converter and a DC-DC converter(s). The topology of the AC-DC conversion module 1 may be determined according to the required output voltage range. In particular, in the case where the load voltage changes, the AC-DC converter and the DC-DC converter may be combined to form the AC-DC conversion module 1.

The controllable current source 4 comprises a comparison module 41 and a constant current source 42 controlled by the comparison module 41. The constant current source 42 is coupled to the output side of the AC-DC conversion module 1, i.e., the power supply circuit 10A. The constant current source 42 may be controlled by the comparison module 41 to be enabled or disabled.

The comparison module 41 acquires the sampling voltage of the voltage detection unit 3, and compares the sampling voltage with a lower limit threshold (also referred to herein as "first threshold") and an upper limit threshold (also referred to herein as "second threshold"), respectively. The comparison module 41 enables the constant current source 42 when the sampling voltage drops below the lower threshold.

The lower limit threshold may be set so that the output voltage Vout of the power supply circuit 10A is within a predetermined amplitude range when the constant current source 42 is enabled. The predetermined amplitude range indicates an ideal range of variation of the output voltage and may be a function of the target output voltage. That is, different target output voltages may correspond to different amplitude ranges. The target output voltage is a load voltage currently required by the electric device including the power supply circuit 10A, is supplied as a command value to the controller 2, and is then supplied as a control signal to the dc conversion controller by the controller 2. As an implementation, the predetermined amplitude range may be determined based on the following formula (1), for example.

Predetermined amplitude range=target output voltage± (a% ×target output voltage+b) (1)

Where a and b may be selected according to the desired voltage stability.

In some embodiments, in order to determine the lower threshold value, the output voltage value (target output voltage) set to the power supply circuit 10A may be continuously adjusted up from the lower limit of the output voltage of the power supply circuit 10A with the constant current source turned off. For example, for a power supply circuit having an output voltage in the range of 20V to 3500V, the output voltage may be set to be continuously adjusted up from 20V. During this process, the actual output voltage of the power supply circuit 10A is measured for different set output voltages, and it is determined whether the actual output voltage is within a predetermined amplitude range. Since the constant current source is not enabled, the fluctuation range of the actual output voltage Vout may exceed the predetermined amplitude range obtained based on the above formula (1), exhibiting instability at low load voltages. Until when the set target output voltage rises to a certain value (for example, 30V), the range of variation of the actual output voltage Vout no longer exceeds the predetermined amplitude range obtained based on the above equation (1), the value (for example, 30V) may be determined as the lower limit threshold for enabling the constant current source 42. When the actual output voltage is above the lower threshold, the target output voltage may be approximated as being above the lower threshold without the constant current source 42 being enabled.

It should be understood that the lower threshold may be for the actual output voltage or for the sampled voltage after dividing the actual output voltage, depending on the voltage measurement mode of the voltage detection unit 3. In the latter case, the lower threshold value set in the comparison module 41 may further consider the voltage division ratio of the voltage detection unit 3 to the output voltage. In other words, if the above-described original lower limit threshold of, for example, 30V is determined for the output voltage Vout, the lower limit threshold set in the comparison module 41 may be determined by multiplying the original lower limit threshold (30V) by the voltage division ratio of the voltage detection unit 3.

By determining the lower threshold as described above, the lower threshold for enabling the constant current source 42 can be determined according to the required voltage stability, and thus the timing for enabling the constant current source 42 can be determined according to the required voltage stability, and premature or late enabling of the constant current source 42 can be avoided.

On the other hand, since the constant current source 42 has a load characteristic, the loss and the heat generation amount thereof do not change with an increase in the voltage across the terminals, but they also constitute one of the factors affecting the efficiency of the power supply circuit 10A. Accordingly, the comparison module 41 may disable the constant current source 42 to make the operating temperature of the power supply circuit 10A lower than a predetermined upper operating temperature limit when the sampling voltage acquired by the voltage detection unit 3 rises beyond a certain upper threshold (also referred to herein as a "second threshold"). The upper threshold is higher than the lower threshold described above.

The upper threshold may be determined in a similar manner to the lower threshold. The output voltage value (target output voltage) set for the power supply circuit 10A may be continuously adjusted up from the lower limit of the output voltage of the power supply circuit 10A with the constant current source turned on. For example, for a power supply circuit having an output voltage in the range of 20V to 3500V, the output voltage may be set to be continuously adjusted up from 20V. During this process, the operating temperature of the power supply circuit 10A is measured for different set output voltages, and it is determined whether the operating temperature exceeds a predetermined upper operating temperature limit. Until the actual operating temperature reaches the predetermined upper operating temperature limit when the set target output voltage rises to a certain value (e.g., 50V), the value (e.g., 50V) may be determined as the upper limit threshold for disabling the constant current source 42.

By determining the upper threshold as described above, the upper threshold for disabling the constant current source 42 can be determined according to the maximum operating temperature, so that the power supply circuit 10A can operate in the safe temperature section.

The constant current source 42 may be enabled or disabled when the sampling voltage is between the lower threshold and the upper threshold, depending on the trend of the sampling voltage. For the case where the sampling voltage rises from a certain value lower than the lower threshold to exceed the upper threshold, the constant current source 42 is first activated when the sampling voltage is lower than the lower threshold. As the sampling voltage rises, the constant current source 42 remains in the enabled state until the sampling voltage rises above the upper threshold and is disabled. During this process, the constant current source 42 remains in an enabled state when the sampling voltage is between the lower threshold and the upper threshold.

On the other hand, in the case where the sampling voltage falls from a certain value higher than the upper threshold value to below the lower threshold value, the constant current source 42 is first disabled when the sampling voltage is higher than the upper threshold value. As the sampled voltage drops, the constant current source 42 remains disabled until it is enabled after the sampled voltage drops below the lower threshold. During this process, the constant current source 42 remains disabled when the sampling voltage is between the lower threshold and the upper threshold. Both processes can be implemented by the comparison module 41.

Although, in the former case, the constant current source 42 remains activated while the sampling voltage is between the lower threshold and the upper threshold, unnecessary loss and heat generation may occur, by setting a buffer between such upper threshold and lower threshold, frequent activation or deactivation of the constant current source 42 can be avoided.

Fig. 2 shows a circuit diagram of an example topology of a wide range voltage tunable power supply circuit 10A in accordance with the techniques of the present disclosure. In the present embodiment, the AC-DC conversion module described with reference to fig. 1 is constituted by a PFC (Power Factor Correction: power factor correction) circuit 13, a BUCK circuit 14, and a flyback direct current conversion circuit controlled by a flyback controller 17.

Specifically, the main power supply 11 may be connected to, for example, a power grid to obtain ac power.

The bridge rectifier module 12 full-wave rectifies the ac power obtained by the main power supply 11 to obtain rectified power bd+.

The PFC circuit 13 performs power factor correction on the rectified ac power bd+ and converts it into dc power b+ having a fixed voltage.

The BUCK circuit 14 steps down the dc power b+ and inputs the stepped down dc power to the primary side of the transformer T of the flyback dc conversion circuit. The BUCK circuit 14 has different ground bits GND, GND1. The dc power b+ is coupled to the ground GND, and both the stepped down dc power and the primary side of the transformer T are coupled to the ground GND1.

A control signal indicating the target output voltage from the controller 2, for example, a PWM signal is converted into a dc signal via an RC filter composed of a resistor R0 and a capacitor C0, and then supplied to the BUCK circuit 14 via the optical isolation amplifier 15. When the target output voltage is low, for example 20V, the duty cycle of the PWM signal provided by the controller 2 decreases, and the filtered dc signal provided to the BUCK circuit 14 decreases accordingly, so that the output voltage of the BUCK circuit 14 decreases further. This can alleviate the low PWM signal duty cycle condition of the flyback controller 17 at low output voltages. In other words, in the present embodiment, the AC-DC converting section of the AC-DC converting module 1 is the PFC circuit 13, and the DC-DC converting section includes the BUCK circuit 14 and a flyback DC converter described below. The BUCK circuit 14 serves as a front-end dc BUCK. The flyback direct current converter plays a role in direct current boosting or reducing according to the output voltage.

The flyback dc converter includes a flyback controller 17 on the primary side of a transformer T, T, a rectifier bridge (not shown) controlled by the flyback controller 17, and one or more rectifier circuits on the secondary side. The rectifying circuit includes a freewheeling diode and an RC filter. As shown in fig. 2, the flywheel diode D1, the resistor R1, and the capacitor C1 constitute a rectifying circuit. The figure shows 14 loops of freewheeling diodes D1-D14, resistors R1-R14, and capacitors C1-C14.

The primary side of the transformer T is coupled to ground GND1 and the secondary side is coupled to ground GND2. The output side of the transformer T is coupled with a feedback resistor R _H 、R _L . Feedback resistor R _L The voltage across the terminals (also referred to herein as the current detection unit) (Vout. R _L /(R _L +R _H ) Is input as a feedback voltage (also referred to as a sampling voltage) to one input of the comparison module 16. The other input of the comparison module 16 receives a control signal from the controller 2, which indicates a target output voltage. The control signal (PWM) is filtered by the capacitor C0 and the resistor R0 and converted into a dc signal, the magnitude of which is a function of the duty cycle of the control signal, which is input to the comparison module 16. The output of the comparison module 16 is coupled via a photo coupler 18 to the feedback terminal of a flyback controller 17.

When the feedback voltage is higher than the control signalAt the target output voltage indicated by the number, the comparison module 16 outputs a drive signal to disconnect the photocoupler 18. Thus, the feedback terminal of the flyback controller 17 cannot receive the feedback voltage and stops operating. When the feedback voltage is lower than the target output voltage indicated by the control signal, the comparison module 16 does not disconnect the photocoupler 18, the feedback resistor R _L Can be input to the feedback terminal of the flyback controller 17 via the optocoupler 18. Flyback controller 17 may drive the flyback dc converter to increase its output voltage based on the feedback voltage until feedback resistor R _L The feedback voltage of (2) reaches the target output voltage and the photo coupler 18 is driven again to be disconnected.

A constant current source 42 is coupled to the output side of the transformer T, which enables and disables the control by the comparison module 41 (first comparison module). Feedback resistor R _L Is input to one input of the comparison module 41. The comparison module 41 will feed back the resistor R _L Is compared with the upper and lower thresholds described above to control the enabling and disabling of the constant current source 42, respectively. Specifically, in response to the feedback resistance R _L The sampling voltage of (a) drops below the lower threshold, the comparison module 41 enables the constant current source 42. Responsive to feedback resistance R _L The sampling voltage of (a) rises to the upper threshold value, and the constant current source 42 is disabled. Thus, for the case where the sampling voltage rises from a certain value lower than the lower threshold to exceed the upper threshold, the constant current source 42 is first activated when the sampling voltage is lower than the lower threshold. As the sampling voltage rises, the constant current source 42 remains in the enabled state until the sampling voltage rises above the upper threshold and is disabled. On the other hand, in the case where the sampling voltage falls from a certain value higher than the upper threshold value to below the lower threshold value, the constant current source 42 is first disabled when the sampling voltage is higher than the upper threshold value. As the sampled voltage drops, the constant current source 42 remains disabled until it is enabled after the sampled voltage drops below the lower threshold.

The buffer manner of setting the upper and lower thresholds can avoid the constant current source 42 being frequently enabled or disabled, but it should be understood that only one threshold may be set for the purpose of simplifying the circuit such that the sampling voltage is enabled below the threshold and disabled above the threshold.

The wide-range voltage-adjustable power supply circuit 10A of the present embodiment can couple the constant current source 42 to the output side at low load voltage to improve voltage stability at low voltage output, and can effectively alleviate ripple in the circuit. In addition, the constant current source 42 can be disabled to reduce losses and heating as the load voltage increases.

Example 2

Since an energy storage element such as a capacitor is present in the power conversion circuit, as shown in fig. 2, when the power supply circuit is turned off, a certain time is required for the entire circuit to discharge energy. That is, it takes a while for the output voltage to drop to a safe value. According to the IEC61010-1 standard, the output voltage needs to be reduced below 70V within 10 seconds after the power supply circuit is turned off. The operator is prohibited from plugging the power cord before the output voltage drops to a safe value, otherwise a hazard may occur. For 20V-3500V power supply circuits, this can be challenging, especially if the device is turned off from high loads. The present embodiment utilizes the load characteristics of the constant current source to increase the energy release rate when the power supply circuit is turned off.

Fig. 3 shows a circuit diagram of an example topology of another example wide range voltage tunable power circuit 10B in accordance with the techniques of this disclosure. In comparison with the power supply circuit 10A shown in fig. 2, the power supply circuit 10B of the present embodiment further includes a controller 5 (also referred to herein as a second controller).

The controller 5 is coupled to the controller 2 via an infrared optical communication module 8. According to the IEC61010-1 standard, a sufficient creepage distance is required between the high voltage circuit and other low voltage conventional circuits. For example, for a main circuit with a maximum 3500V output, the creepage distance should be greater than 70mm and the spacing should be greater than 13.8mm. The infrared optical communication module 8 is one solution. The infrared optical communication module 8 is constituted by infrared emitter-phototransistor pairs on both sides, whereby the controller 5 can be isolated from the controller 2 of the main circuit and data transmission of both can be achieved.

The controller 5 may be coupled to a display 6 and an input device such as a touch screen 7. The AC-DC conversion module 9 picks up auxiliary power from the main power supply 11 and converts it to auxiliary direct current power (e.g., 12V) to be supplied to the controller 5, the optional display 6, the optional touch screen 7, and the controller 5 side of the infrared optical communication module 8.

In this embodiment, the controller 2 is also coupled to a feedback resistor R _L To obtain the feedback resistance R _L Is provided. The controller 2 is also coupled to the constant current source 42 and is capable of outputting a Discharge mode enable signal discharge_en to the constant current source 42 to control the enabling and disabling of the constant current source 42.

When an operator inputs an instruction to turn off the electric equipment through the touch screen 7, the controller 5 sends an interrupt instruction to the controller 2 through the infrared optical communication module 8. In response to receiving the interrupt instruction, the controller 2 adjusts the duty ratio of the PWM signal supplied to the flyback controller 17 and the BUCK circuit 14 to 0. The PWM signal with a duty ratio of 0 is filtered by the capacitor C0 and the resistor R0 to become a 0V dc voltage, which is input to the flyback controller 17, which stops the circuit and enters the discharge mode. At the same time, the controller 2 outputs a Discharge mode enable signal discharge_en having a value of "1" to the constant current source 42 to enable the constant current source 42. Due to the load characteristics of the constant current source 42, the release of energy in the circuit can be accelerated, so that the output voltage of the circuit can be reduced below a safe value more quickly.

During the discharge mode, the controller 2 will feedback the resistor R _L Is sent to the controller 5 via the infrared optical communication module 8. The transmission of the sampled voltage may be in real time or periodically, or may be in response to a query from the controller 5. The controller 5 may cause the display 6 to display the sampled voltage or the output voltage Vout corresponding to the sampled voltage to enable an operator to visually grasp the remaining voltage of the circuit. The output voltage Vout may be calculated by the controller 2 and transmitted to the controller 5. During the discharge mode, the controller 5 may also cause the display 6 to display a warning to organize the operator to plug the power cord.

When the sampling voltage or the output voltage Vout calculated from the sampling voltage decreases to a predetermined safety value, the controller 2 may disable the constant current source 42 to end the discharge mode. At the same time, the controller 2 may cause the display 6 to no longer display a warning. Depending on the way the user enters the closing instruction, e.g. interrupting the device or closing the device, the display 6 may be caused to display a corresponding picture. At this time, the user can safely plug the power cord or perform other operations after power failure.

If the controller 5 receives an instruction to interrupt or stop the operation of the power supply circuit 10B via an input device such as the touch screen 7 in block 402, the controller 5 transmits an interrupt instruction to the controller 2 in block 404. Upon receiving the interrupt instruction, the controller 5 adjusts the duty ratio of the PWM signal output to the LC filter constituted by the capacitor C0 and the resistor R0 to stop the operation of the power supply circuit 10B. At the same time, the controller 5 sends an enable signal, such as a discharge_en signal having a value of "1", to the constant current source 42 to enable the constant current source 42.

In block 406, the controller 5 may cause an output device, such as the display 6, to display a warning to prevent unsafe operation by an operator, such as plugging in and out a cable. The controller 5 may also cause the display 6 to display the residual voltage. The residual voltage can be based on the resistor R obtained by the controller 2 _L Is determined by the voltage across (sampled voltage of) the capacitor. The controller 2 may send the sampled voltage to the controller 5 in real time, periodically or in response to a query by the controller 5.

The controller 5 may compare the sampled voltage obtained from the controller 2 with a safe value. In response to the sampled voltage falling below the safe value (yes in block 408), an instruction may be output to the controller 2 to cause the controller 2 to end the discharge mode. The controller 2 may 5 send a disable signal, such as a disable_en signal having a value of "0", to the constant current source 42 to disable the constant current source 42. At the same time, the controller 5 may cause the display 6 to stop the display of the warning and the residual voltage. If it is determined in block 408 that the voltage drop is above the safe value, the process returns to block 406.

In another embodiment, the comparison of the sampled voltage with the safety value may be performed by the controller 2. And when the sampled voltage falls below the safe value (yes in block 408), an instruction is sent by the controller 2 to the controller 5 to stop the display of the warning and the residual voltage.

In the present embodiment, in interrupting the operation of the power supply circuit 10B, the controller 2 adjusts the duty ratio of the output PWM signal to 0, the constant current source 42 may be enabled based on the start of the discharge mode and disabled based on the end of the discharge mode. Therefore, not only can the stability at the time of low load operation be achieved by the constant current source 42 during the low voltage operation (PWM duty is lower but higher than 0) of the power supply circuit 10B, but also the energy release of the circuit can be accelerated by the load characteristic of the constant current source 42 at the time of interrupting or turning off the power supply circuit 10B, so that the residual voltage of the power supply circuit 10B is reduced to the safety level more quickly. Further, by displaying a warning and/or a residual voltage during discharge, an operator can be prevented from performing unsafe operation before the residual voltage of the power supply circuit 10B drops to a safe level more quickly.

The embodiments, implementations and aspects described above have been described in order to allow easy understanding of the utility model and are not limiting of the utility model. On the contrary, the utility model is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as is permitted under the law.

Claims

1. A wide range voltage tunable power supply circuit, comprising:

a first AC-DC conversion module configured to convert an AC input power into a DC output power based on a control signal;

a voltage detection unit configured to sample an output voltage of the first AC-DC conversion module; and

a controllable current source comprising:

a constant current source coupled to an output side of the first AC-DC conversion module; and

a first comparison module is coupled to the constant current source and the voltage detection unit and configured to enable the constant current source in response to a sampled voltage of the voltage detection unit decreasing below a first threshold.

2. The wide range voltage adjustable power supply circuit of claim 1, wherein the first comparison module is further configured to disable the constant current source in response to the sampling voltage rising above a second threshold, wherein the second threshold is higher than the first threshold.

3. The wide range voltage tunable power supply circuit according to claim 2, wherein the constant current source is disabled before the sampling voltage decreases from above the second threshold to below the first threshold.

4. The wide range voltage adjustable power supply circuit according to claim 1, wherein said first threshold is set such that said output voltage of said wide range adjustable power supply circuit is within a predetermined amplitude range when said constant current source is enabled.

5. The wide range voltage adjustable power supply circuit of claim 2, wherein the second threshold is set such that when the constant current source is enabled, the operating temperature of the wide range adjustable power supply circuit is below a predetermined upper operating temperature limit.

6. The wide range voltage tunable power circuit of any one of claims 1 to 5, further comprising a first controller coupled to the voltage detection unit and the first AC-DC conversion module and configured to provide the control signal to the first AC-DC conversion module based on the sampled voltage,

the first AC-DC conversion module includes:

a PFC circuit configured to convert the ac input power to dc power;

a BUCK circuit coupled to the first controller and configured to receive the dc power and step down the dc power based on the control signal from the first controller; and

a BUCK/BOOST circuit is coupled to the BUCK circuit and the first controller and is configured to voltage convert the stepped down dc power as the dc output power based on the control signal.

7. The wide range voltage tunable power supply circuit of claim 6, wherein the BUCK/BOOST circuit is a flyback dc conversion circuit comprising a transformer, a primary side of the transformer comprising a flyback controller, and a secondary side comprising:

at least one loop consisting of a freewheeling diode and a first RC filter; and

and the output end of the second comparison module is coupled to the feedback end of the flyback controller through a photoelectric coupler.

8. The wide range voltage tunable power circuit of claim 7, further comprising a second controller communicatively coupled with the first controller and configured to: transmitting an interrupt instruction to the first controller in response to a user input indicating to stop or interrupt operation of the power supply circuit,

wherein, the control signal is a PWM signal,

the first controller is further configured to:

in response to receiving the interrupt instruction, adjusting a duty cycle of the control signal to 0 to cause the power supply circuit to enter a discharge mode; and is also provided with

The sampling voltage is transmitted to the second controller in real time or periodically during the discharge mode.

9. The wide range voltage tunable power circuit of claim 8, wherein the second controller is further configured to: in response to the received sampling voltage being below a third threshold, sending an instruction to the first controller to stop the discharge mode,

the first controller is further configured to: and stopping sending the sampling voltage to the second controller in response to receiving an instruction to stop the discharge mode.

10. The wide range voltage adjustable power supply circuit of claim 9, wherein the first controller is coupled to the constant current source and is further configured to:

enabling the constant current source during the discharge mode; and is also provided with

In response to ending the discharge mode, the constant current source is disabled.