System and method for determining the main power supply voltage

Abstract

A secondary side controller is configured to determine a peak voltage and / or a frequency of a secondary winding of a converter of a power supply over a predetermined period of time, and the secondary side controller is configured to instruct the primary side controller to increase a set point when the converter is in burst mode, causing the primary side controller to operate in standard mode to increase the conversion output voltage, and the secondary side controller determines the peak voltage and / or the frequency of the secondary side winding while the primary side controller is operating the converter in standard mode.

Description

Technical Field

[0003] , ,

[0004]

[0001] The following relates to a system and method for determining the main power supply voltage of a power supply, and particularly to the determination of the main power supply voltage of a power supply when the converter of the power supply is operating in burst mode.

Background Art

[0002] Currently, many LED drivers are designed with isolated outputs and use a secondary-side controller to adjust the output voltage or current to a target value. With the evolution of LED drivers towards digital interfaces such as DALI or the like, LED drivers are also increasingly adding more diagnostic functions. Furthermore, standardization bodies such as DiiA require certain specific diagnostics for products bearing the D4i logo. These diagnostics include items such as LED voltage and current, but also include main power supply voltage-related items such as main power supply voltage, power factor, and main power supply frequency. In many of these isolated topologies, it is difficult to measure main power supply-related parameters because the secondary-side controller is isolated from the primary side where the main power supply voltage is received. Therefore, when the controller is isolated from the primary side, it is desirable to directly measure these diagnostic items from the secondary side.

Summary of the Invention

Problems to be Solved by the Invention

[0003] Furthermore, when the input stage operates in burst mode due to a light load condition, the accuracy of detecting the main power supply voltage and frequency from the isolated secondary side decreases because the burst operation is independent of the main power supply voltage and frequency. Therefore, in the art, there is a need to determine the main power supply voltage and frequency from the secondary side of a power supply, especially when the power supply input stage can operate in burst mode or standard mode.

Means for Solving the Problems

[0004] The examples described herein can be combined in any way that is technically possible.

[0005] According to one embodiment, a power supply having secondary side mains measurement is a converter configured to receive an input voltage and supply a converted output voltage, comprising a transformer having a primary side winding and a secondary side winding, a transformer defining the primary and secondary sides of the power supply, wherein the primary side includes a transformer that is galvanically isolated from the secondary side, and a switch arranged to interrupt or enable the flow of current through the primary side winding of the transformer, and a primary side controller configured to operate the converter via a drive signal supplied to the switch, wherein the converted output voltage is set to a target set value. A primary-side controller that operates the converter to maintain it at a certain point, wherein the converter is operated in burst mode when the resistance of a load connected to the output terminal of the power supply exceeds a threshold, and the converter is operated in standard mode when the resistance of the load is less than the threshold, or when the primary-side controller is operating the converter to increase the conversion output voltage; and a secondary-side controller configured to determine the peak voltage and / or frequency of the secondary-side winding over a predetermined period, wherein when the converter is in burst mode, the secondary-side controller is configured to instruct the primary-side controller to increase the set value so that the primary-side controller operates in standard mode to increase the conversion output voltage, and the secondary-side controller determines the peak voltage and / or frequency of the secondary-side winding while the primary-side controller is operating the converter in standard mode.

[0006] In the example, the secondary controller is configured to supply the remote computing device with an estimated mains power voltage and / or mains power frequency based on the peak voltage and / or frequency.

[0007] In this example, the secondary controller is further configured to instruct the primary controller to decrease the set value.

[0008] In this example, the secondary controller is configured to instruct the primary controller to increase the set value by changing the error signal supplied to the primary controller.

[0009] In the example, the power supply further includes an amplifier configured to generate the error signal, the amplifier receiving a first input representing the converted output voltage and a second input which is a reference input, the error signal is based on the difference between the converted output voltage and the reference input, and the secondary controller is configured to change the feedback of the error signal by adjusting the reference input.

[0010] In this example, the converter is a flyback converter.

[0011] In this example, the primary controller is a power factor correction controller.

[0012] In this example, the secondary winding is an auxiliary winding.

[0013] In the example, the setting value is increased over a predetermined period of time so that the primary controller operates the converter in the standard mode for a transient period of time long enough to measure the peak voltage and / or the frequency.

[0014] In the example, the setpoint is increased by a predetermined amount, which is selected by the primary controller to cause the converter to operate in the standard mode for a period of time long enough to measure the peak voltage and / or the frequency.

[0015] In another embodiment, the microcontroller comprises a processor and a non-temporary storage medium, the non-temporary storage medium, when executed by the processor, a step of determining the peak voltage and / or frequency of the secondary winding of a transformer over a predetermined period of time, the transformer being used in a power converter, the converter being configured to receive an input voltage and supply a converted output voltage, the transformer defining the primary and secondary sides of the power supply, the primary side being galvanically isolated from the secondary side, the converter further comprising a switch arranged to interrupt or enable the flow of current through the primary winding of the transformer, the microcontroller being arranged on the secondary side of the power supply, and the The primary controller, configured to operate the converter via a drive signal supplied to a switch, stores program code that includes the steps of determining whether it is operating in burst mode or standard mode according to the peak voltage and / or frequency, wherein the primary controller operates the converter to maintain the converted output voltage at a target setpoint; instructs the primary controller to increase the setpoint so that it operates in standard mode to increase the converted output voltage; and determines the peak voltage and / or frequency of the secondary winding while the primary controller is operating the converter in standard mode.

[0016] In an example, the program code further includes the step of supplying a remote computing device with an estimated mains voltage and / or mains frequency based on the peak voltage and / or frequency of the secondary winding, which is determined while the converter is operating in the standard mode.

[0017] In the example, the program code further includes the step of instructing the primary controller to decrease the set value after determining the peak voltage and / or frequency of the secondary winding.

[0018] In the example, the step of instructing the primary controller to increase the set value includes the step of changing the error signal supplied to the primary controller.

[0019] In the example, the step of changing the error signal includes the step of increasing the reference voltage of the error amplifier, and the error amplifier compares the converted output voltage with the reference voltage.

[0020] In the example, the converter is a flyback converter.

[0021] In the example, the primary controller is a power factor correction controller.

[0022] In the example, the secondary winding is an auxiliary winding.

[0023] In the example, the set value is increased over a predetermined period so that the primary controller operates the converter in the standard mode for a time long enough to measure the peak voltage and / or the frequency.

[0024] In the example, the set value is increased by a predetermined amount selected so that the primary controller operates the converter in the standard mode for a time long enough to measure the peak voltage and / or the frequency.

[0025] Referring to the following embodiments, these and other aspects of the various embodiments are described and clarified.

Brief Description of the Drawings

[0026] [Figure 1] It is a schematic diagram of a power supply including a secondary controller configured to measure the main power supply voltage from the voltage of the secondary winding of a transformer. [Figure 2A] It is a plot of the rectified main power supply voltage, auxiliary winding voltage, and bus voltage of a power supply including a flyback converter operated in the standard mode. [Figure 2B] A plot of the rectified main power supply voltage, auxiliary winding voltage, and bus voltage of a power supply including a flyback converter operable in burst mode. [Figure 3] A plot of the rectified main power supply voltage, auxiliary winding voltage, and bus voltage of a power supply including a flyback converter when the voltage set value of the flyback converter is increased. [Figure 4A] A method for determining the main power supply voltage from the secondary side winding of a power supply including a converter operable in standard mode or burst mode. [Figure 4B] A method for determining the main power supply voltage from the secondary side winding of a power supply including a converter operable in standard mode or burst mode.

Best Mode for Carrying Out the Invention

[0027] Various examples described herein are directed to systems and methods for determining the main power supply voltage from the secondary side of a power supply when the power supply is operating in standard mode or burst mode. FIG. 1 illustrates a power supply 100 having a converter that uses a transformer to maintain galvanic isolation between a primary side and a secondary side and is configured to detect the main power supply voltage and / or frequency from the secondary side. As shown in FIG. 1, the power supply 100 receives an input voltage obtained from the main power supply voltage and includes a flyback converter 102 that is operated by a primary side controller U1 to maintain the converted output voltage (bus voltage) at a target setpoint value. The power supply 100 includes a transformer (composed of windings L1, L2, and L3 in FIG. 1) used in the flyback converter 102, which defines the primary and secondary sides of the power supply that are galvanically isolated from each other. The power supply 100 further includes a secondary side controller U2 configured to determine the main power supply voltage and / or main power supply frequency according to the secondary side winding of the flyback.

[0028] For the purposes of this disclosure, the flyback converter 102 includes a transformer (formed by windings L1, L2, and L3), a switch Q1, an output diode D1, and an output capacitor C1. The transformer galvanically isolates the primary side of the power supply, which receives the input mains voltage, from the secondary side, which outputs the converted output voltage, referred to in this disclosure as the bus voltage and shown as the bus voltage in Figure 1. The transformer includes a primary winding L1 which is magnetically coupled to a secondary winding L2 and an auxiliary winding L3. The current through the primary side of the transformer is controlled by a switch Q1 (e.g., a MOSFET, but any suitable switch can be used) which is arranged to alternately interrupt or enable the flow of current through the primary winding L1. The voltage of the secondary winding L2, induced by the magnetic field of the primary winding, is rectified by the diode D1 and smoothed by the capacitor C1. The voltage across the capacitor C1, i.e., the bus voltage, is the converted output voltage of the flyback converter 102.

[0029] The operation of the flyback converter 102 is generally understood, and therefore only a brief summary is provided here for completeness. When switch Q1 is closed, current is allowed to flow through the primary winding L1, storing energy in the transformer. This phase, when switch Q1 is closed and current is flowing through the primary winding L1, is known as the "forward phase". Since the secondary winding L2 is wound in the opposite direction to the primary winding L1, diode D1 is reverse-biased during the forward phase, preventing current from flowing through the secondary winding L2. When switch Q1 is opened, (initiating the phase known as the "flyback phase") the transformer begins to discharge, the voltage across the secondary winding L2 reverses, forward-biasing diode D1 and charging capacitor C1. By discharging the transformer through diode D1 multiple times during each mains power cycle, the voltage across capacitor C1 is kept substantially constant, forming the target converted output voltage (bus voltage) at the output of the flyback converter 102.

[0030] Those skilled in the art will understand that the flyback converter 102 has been simplified for the sake of clarity. In various alternative examples, the flyback converter 102 may include additional components to improve performance. One such addition to the flyback converter 102 is a clamp circuit placed across the primary winding L1 to reduce the ringing waveform at the drain of switch Q1 introduced by the stray capacitance in the flyback converter 102. Such a clamp circuit connected in parallel with the primary winding L1 may include, for example, a parallel combination of a resistor and a capacitor connected in series with a reverse bias diode. This clamp circuit serves to absorb leakage current when the drain voltage exceeds the capacitor voltage, and thus attenuates the ringing. Other circuits (e.g., an RC snubber circuit) may also be introduced into the flyback converter 102 to improve performance.

[0031] While Figure 1 shows a flyback converter 102, it should be understood that the flyback converter is only one example of the type of converter that can be used in power supply 100. In fact, any suitable converter that uses a transformer to maintain galvanic isolation from the primary and secondary sides of the transformer (e.g., active clamp forward converter, single switch forward converter, two switch forward converter, push-pull converter, half-bridge converter, full-bridge converter, etc.) can be used. The operation of such alternative converters is generally understood and will therefore not be described in detail.

[0032] The power supply 100 may further include an input stage to the flyback converter 102, which is designed to adjust the mains power supply voltage input to the flyback converter 102 in a manner that favorably improves the performance of the flyback converter 102. For example, the power supply 100 may include an EMI filter 104 and a rectifier 106. The EMI filter 104 functions to remove high-frequency noise present in the input mains power supply voltage. Such an EMI filter 104 is well known in the art and in various examples may include any combination of an across-the-line capacitor, a common-mode choke coil, a line bypass capacitor, and a normal-mode choke coil, among several potential components. The rectifier 106 functions to rectify the input AC mains power supply voltage and may be formed from, for example, a diode bridge. Other input stages for appropriately adjusting the mains power supply voltage for use by the converter are also conceivable and may be included in various alternative examples.

[0033] Similarly, the power supply 100 may include an output stage, represented here by output stage 108. Output stage 108 may function to further adjust the output voltage of the flyback converter 102. In various examples, output stage 108 may be an additional converter, such as a buck converter, for stepping down the bus voltage to a target value. Thus, the output of power supply 100 may be the output of an output stage, rather than the converted output voltage (bus voltage) of the flyback converter 102 (or any other converter used). Furthermore, it should be understood that additional or different types of output stages may be employed as needed to further adjust the bus voltage (e.g., step down or step up, smoothing, etc.).

[0034] The primary side controller U1 supplies a gate drive signal to switch Q1 to maintain a target output voltage or output current (referred to as the “setpoint”) (maintaining the target output current can be thought of as setting the voltage to the target output voltage depending on the resistance of a given connected load). Any number of suitable primary side controllers (including analog controllers or microcontrollers, or combinations of one or more microcontrollers and associated hardware) can be used to adjust the output voltage or current, but the primary side controller U1 is generally used as a power factor correction (PFC) controller. A PFC controller is an analog controller or microcontroller designed to adjust the output of a power supply by changing the gate drive signal to maintain the power factor and output voltage or current of the power supply at a target voltage or current value. As mentioned above, the target power factor and / or target output voltage do not need to be constant and can vary depending on the circumstances. For example, in some cases, the setpoint may vary depending on the load resistance to maintain a constant current.

[0035] The primary side controller U1 operates in either standard mode or burst mode, depending on the magnitude of the load connected to the output terminal. More specifically, when the load resistance is below a certain value (referred to as a threshold), the power consumed by the load is greater than the power threshold required for operation in standard mode, and therefore the primary side controller operates in standard mode. However, when the load resistance is greater than the threshold, the power consumed by the load is less than the power threshold required for operation in standard mode, and therefore the primary side controller operates in burst mode, where a gate drive signal is supplied to close switch Q1 at a frequency significantly lower than the frequency at which it operates in standard mode.

[0036] During the forward phase of each switching cycle, energy is stored in the primary magnetization inductance of the transformer, and the output capacitor C1 is discharged to the load. During the flyback phase, the energy stored on the primary side is released to the secondary side, and the output capacitor C1 is charged. In standard mode operation, the charging and discharging energies within each switching cycle are balanced. Burst mode arises because, when the load resistance is high, the output capacitor C1 discharges at a significantly slower rate than when the load resistance is low. There is a controller-based minimum amount of energy stored on the primary side. As a result, during the flyback phase, the output voltage of capacitor C1 is charged more quickly than the target output voltage, a voltage that would not discharge during the next forward phase, as would normally occur with a lower resistance load. Therefore, the primary side controller U1 increases the time between consecutive forward phases (i.e., the time between consecutively closing switches Q1) to avoid charging capacitor C1 to a value higher than the target output voltage, which would occur if the primary side controller U1 remained in standard mode. The detailed characteristics of the burst mode (e.g., the frequency and magnitude of the supplied burst) vary depending on the primary controller.

[0037] To regulate the bus voltage, the primary controller U1 can receive a feedback error signal representing the bus voltage error, i.e., the degree to which the bus voltage deviates from the target voltage. The feedback error signal may be based, for example, on a comparison of the output voltage or current with a reference signal. This is shown in Figure 1, where the error amplifier 112 generates an output based on the difference between the bus voltage and the reference signal (bus control). This output error detection signal may be supplied to the primary controller U1 via the optocoupler U3 to maintain galvanic isolation between the primary and secondary sides. The flyback converter adjusts the pulse width of the gate drive signal (i.e., pulse width modulation) according to the magnitude of the feedback signal received from the error amplifier 112 or the secondary controller U2 via the optocoupler U3 to maintain the bus voltage at the target setpoint.

[0038] The error amplifier 112 can take on various appropriate forms. In the example in Figure 1, the error amplifier has an operational amplifier U4 and resistors R1, R2, R3, and R4. The operational amplifier outputs a signal that is proportional to the difference between the input at R1, which is the bus voltage input in this example, and the input at R3, which is the bus control input in this example (i.e., it has some gain). Furthermore, capacitors C3 and C4 form a compensation network selected to address overshoot and undershoot problems when the input voltage undergoes some abrupt change. The values ​​of R1 to R5 and C3 to C4 are design choices that can be selected to set the output gain and the degree to which undershoot and overshoot are prevented. Furthermore, it should be understood that the example of the error amplifier 112 with the associated components R1 to R5 and C2 to C3 as configured in Figure 1 is only one example of an appropriate error amplifier. In various alternative examples, the error amplifier 112 can be formed by any circuit suitable for detecting the difference between the bus voltage and the reference signal and supplying an error signal proportional to the difference.

[0039] In this example, the input to the error amplifier 112 is a reference signal, and the other input, the bus voltage, is a bus control signal which is a reference signal compared to the reference signal. Therefore, the output of the error amplifier 112 is proportional to the difference between the bus voltage and the bus control reference signal. As will be explained below, the bus control signal may be supplied by the secondary controller U2. Therefore, in this example, the reference, which the bus voltage is compared to, is indicated by the secondary controller U2.

[0040] In an alternative example, the comparison between the bus voltage and the reference voltage can be performed within the secondary controller U2 and therefore can be entirely carried out by firmware or software (omitting the error amplifier 112). In this example, the bus voltage is supplied to the microcontroller U2, which compares this input with the reference voltage (using an internal comparator). The reference voltage can be generated internally or received at the reference voltage input to the controller U2. Furthermore, in this example, the difference between the bus voltage and the reference voltage can be output from the secondary controller U2 to the primary controller via the optocoupler U3.

[0041] In the above example, it should be understood that the bus voltage input to either the error amplifier 112 or the secondary controller U2 can be supplied to the error amplifier 112 or the secondary controller U2 as a voltage representing the bus voltage. More specifically, since the bus voltage can be relatively high in some examples, the bus voltage may be stepped down before being input to the error amplifier 112 or the secondary controller U2. Therefore, the bus voltage input to the error amplifier 112 or the secondary controller U2 may be an input proportional to the bus voltage, rather than the bus voltage itself.

[0042] When the primary side controller U1 is in standard mode and the flyback converter 102 is in forward phase (i.e., when switch Q1 is closed and current is flowing through the primary winding L1), the voltage across any secondary side winding of the transformer (e.g., L2 or L3) is proportional to the mains power supply voltage. Thus, the mains power supply voltage can be detected on the secondary side by measuring the voltage across either the secondary side winding L2 or the auxiliary winding L3. In this manner, the voltage across the secondary side winding of the transformer acts as a proxy, by which the mains power supply voltage can be measured on the secondary side of the power supply.

[0043] In the example in Figure 1, auxiliary winding L3 is used instead of secondary winding L2. This is because auxiliary winding L3 generally contains fewer turns and therefore has a lower output voltage. As a result, less power is consumed when the voltage across auxiliary winding L3 is stepped down for measurement, resulting in fewer grounding problems that can generally occur with the higher-power secondary winding L2. Furthermore, it should be understood that auxiliary winding L3 is just one example of an auxiliary winding that may be used. In fact, a transformer can contain any number of potential auxiliary windings, any of which can be used to detect the mains voltage and / or frequency as needed. In fact, although the following explanation relating to Figure 1 refers to the voltage across auxiliary winding L3, it should be understood that any secondary winding can be used.

[0044] In the example in Figure 1, the secondary controller U2 measures the voltage across the auxiliary winding L3 at an input labeled "Mains Power Peak." This input is the output of a peak detector 110 connected across the auxiliary winding L3. Since the voltage across the auxiliary winding L3 is proportional only to the rectified mains power voltage when the flyback converter is in the forward phase, the peak detector 110 is used to detect the peak (i.e., envelope) of the voltage across the auxiliary winding L3, and thus reproduces a signal at the input of the secondary controller U2 that is substantially proportional to the mains power voltage. The peak voltage of the auxiliary winding can be measured by measuring the voltage across the peak winding L3 over a predetermined period (e.g., half a cycle of the mains power voltage) (the peak voltage refers to the maximum voltage occurring within a periodic half-cycle of the mains power voltage). The peak voltage of the auxiliary winding is proportional to the peak voltage of the mains power voltage and can therefore be used to determine the mains power voltage value (e.g., as a peak-to-peak value or RMS value).

[0045] Furthermore, the frequency of the mains power supply voltage can be identified by the secondary controller U2 by measuring the elapsed time between zero crossings of the auxiliary winding voltage or any other repeating, identifiable portion of the waveform (e.g., a peak). The time between zero crossings or other repeating, identifiable portions of the waveform can be measured, for example, by counting the microcontroller clock cycles (of the secondary controller U2 clock) between consecutive instances of the zero crossing or identifiable portion. The determined mains power supply voltage and / or frequency can be output as diagnostic information to a connected or remote device according to the method described in more detail below.

[0046] The secondary controller U2 may be implemented in various examples as one or more microcontrollers, as hardware, or as a combination of one or more microcontrollers and hardware, configured to perform the steps and functions described in this disclosure.

[0047] In the example shown, the peak detector 110 may consist of a diode D2 and a capacitor C2. Diode D2 allows current to flow and charges capacitor C2 when the flyback converter 102 is in the forward phase, and blocks the current flow when the flyback converter 102 is in the flyback phase. Since capacitor C2 does not discharge immediately when the flyback converter 102 is in the forward phase, the voltage across capacitor C2 follows the envelope of the forward phase voltage and accurately represents the rectified main voltage signal.

[0048] In alternative examples, the peak detector 110 may further include a circuit (e.g., a voltage divider) for stepping down the voltage across the auxiliary winding (e.g., to keep the voltage within an acceptable voltage range at the input of the secondary controller U2). Furthermore, it should be understood that the peak detector 110 in Figure 1 is shown only as an example, and any suitable peak detector may be used. In alternative examples, peak detection can be performed internally in the controller U2 (e.g., in software or firmware), and therefore the peak detector 110 may be omitted.

[0049] However, when the primary side controller U1 operates in burst mode, the voltage of the auxiliary winding cannot be easily associated with the mains voltage. In fact, during bursts, the voltage of the auxiliary winding L3 represents the rectified mains voltage, but these bursts may not occur at the peak of the rectified mains voltage, the burst repetition rate is independent of the mains frequency, and therefore the voltage and frequency of the rectified mains voltage cannot be identified.

[0050] This can be seen by comparing Figures 2A and 2B, which illustrate plots of the peak detection auxiliary winding voltage, rectified mains voltage, and converted output voltage in standard mode (Figure 2A) and burst mode (Figure 2B). As shown in Figure 2A, the peak detection auxiliary winding voltage 200A closely follows the example of the peak detection rectified mains voltage 202A (measured at the input to the primary winding). However, as shown in Figure 2B, in burst mode, considering how infrequently the primary winding is conducting, the peak detection rectified mains voltage 202B is not similar to the mains voltage in terms of magnitude or frequency. Therefore, meaningful information about the mains voltage cannot be confirmed from the peak detection auxiliary voltage 200B that follows the burst of the primary winding L1.

[0051] Therefore, the secondary controller U2 may be configured to detect when the primary controller U1 is operating in burst mode and to increase the voltage setpoint of the primary controller U1 so that the primary controller U1 increases the output bus voltage before measuring the mains voltage on the secondary side of the transformer, thereby pulling the primary controller U1 from burst mode to normal mode operation.

[0052] Figure 3 shows what happens to the signal shown in Figure 2 when the bus voltage is forced to a new setpoint in a typical LED driver operating in burst mode. As shown, as soon as the bus voltage setpoint 204C is increased by the secondary controller U2, the primary controller U1 attempts to increase the bus voltage back to the new setpoint, thereby forcing it into non-burst operation for approximately 10 mains power half-cycles. During these cycles, the peak-sensing rectified mains power voltage in the primary winding 202C and the voltage 200C in the peak-sensing auxiliary winding L3 correspond precisely to the input mains power voltage, allowing both the mains power voltage and frequency to be precisely determined during this period.

[0053] By adjusting the voltage step to be sufficiently large, it can be ensured that the primary side controller U1 remains in standard mode for at least one half-cycle of the rectified mains power signal so that the peak voltage is captured. In other examples, the voltage step can be made large enough to ensure that the primary side controller U1 remains in standard mode for at least one rectified mains power cycle so that at least two zero crossings are detected and the mains power frequency can also be determined.

[0054] However, depending on the primary controller U1, even large voltage steps may occur within a time shorter than half a cycle, so there is no guarantee that the primary controller U1 will remain in normal operation over half a cycle or a full cycle. Accordingly, the secondary controller U2 can increase the setpoint multiple times or continuously during half a cycle or a full cycle, and the flyback converter will attempt to meet the changing setpoint, ensuring that it remains in standard mode for the length of time required to capture the mains voltage or frequency.

[0055] In the example in Figure 1, the secondary controller U2 can change the setpoint by modifying the bus control input to the amplifier to alter the error signal, thereby indicating to the primary controller U1 that the bus voltage is too low. In other words, the secondary controller U2 can increase the bus control voltage, increasing the difference between the bus voltage and the bus control voltage, and consequently increasing the magnitude of the error signal feedback to the primary controller U1. As a result, the primary controller U1, receiving feedback that the bus voltage is too low, enters normal operation to increase the bus voltage.

[0056] In an alternative embodiment, the secondary controller U2 can output a signal directly to the primary controller U1 (e.g., via the optocoupler U3) to increase the voltage setpoint, independently of the error amplifier 112. For example, the output of the secondary controller U2 can be supplied to the feedback input of the secondary controller U2 in addition to or as a substitute for the feedback input from the error amplifier 112. For example, as described above, the secondary controller U2 can replace the error amplifier 112 and perform a comparison between the bus voltage and the reference signal. In this example, the error sensor signal is supplied to the primary controller U1 from the secondary controller U2, not from the error amplifier 112. In another example, the feedback signal can be supplied to the primary controller U1 from both the secondary controller U2 and the error amplifier 112. For example, both the error detection signal and the output from the secondary controller U2 can be supplied to the optocoupler, and the larger of these determines the feedback signal input to the primary controller U1, allowing the secondary controller U1 to override the feedback input from the error amplifier 112 and set the voltage output accordingly.

[0057] In another example, a pin other than the feedback pin to the primary controller U1 may be used to increase the setpoint. For example, the primary controller U1 may include a setpoint pin, the input to which this setpoint pin indicates a setpoint for the bus voltage. In this example, the secondary controller U1 may change the input to this pin to increase the setpoint and allow the controller U1 to enter standard mode for a sufficient amount of time to measure the mains voltage and frequency.

[0058] If the secondary controller U2 increases the setpoint to ensure that the primary controller U1 operates in standard mode for a sufficient period of time to acquire the mains voltage and / or frequency, the secondary controller U2 can decrease the setpoint back to its previous value. In the example in Figure 1, this can be achieved by decreasing the bus control signal back to its value before the increase. The bus control signal can remain at a lower value until the mains voltage and / or frequency needs to be read again and the setpoint can be increased again.

[0059] The secondary controller U2 can determine whether the primary controller U1 is in burst mode by comparing the voltage or frequency of the auxiliary winding L3 with a threshold. When the primary controller U1 is in burst mode, the output of the auxiliary winding L3 does not rise above a certain threshold and does not exceed a certain frequency. Therefore, the secondary controller can determine whether the primary controller U1 is in burst mode by monitoring the auxiliary winding L3 over half a cycle (to compare the voltage with the threshold) or over a full cycle (to compare the frequency with the threshold).

[0060] The secondary controller U2 can be configured to determine the mains voltage and frequency from the measured auxiliary winding voltage. The peak auxiliary winding voltage in a given half-cycle is likely to be related to the mains voltage by some proportionality constant. Therefore, the secondary controller U2 can be configured to determine the mains voltage by multiplying the measured peak voltage of the auxiliary winding by a proportionality constant. The frequency of the auxiliary winding is likely to be the same as the frequency of the mains voltage, but the secondary controller also converts the measured frequency to the frequency of the mains voltage to the extent that the intervening circuit changes the measurement frequency in the secondary controller.

[0061] The secondary controller U2 can be configured to transmit the measured mains voltage to a remote device via a wired or wireless connection using any suitable protocol (e.g., DALI, Bluetooth, ZigBee, NFC, etc.). In fact, as mentioned above, certain standardization bodies such as DiiA require that products bearing the D4i logo be able to supply diagnostic information such as output voltage and frequency, as well as mains voltage-related items such as mains voltage, mains frequency, and power factor. Such a remote device may be a mobile device or a computer. The remote device can be configured to display the diagnostic information to the user, for example, on a dashboard, so that the user can monitor the mains voltage and / or frequency.

[0062] In alternative examples, the secondary controller U2 may be configured not only to change the setpoint to determine the mains voltage and / or frequency, but also to periodically change the voltage setpoint to improve the efficiency of the flyback converter. More specifically, in instances where the bus voltage value is not critical (i.e., when the power supply is in standby mode), the bus voltage setpoint may be continuously changed to keep the primary controller U1 in normal operation. In these examples, the output stage 108 may be turned off so that there is no bus voltage at the power supply output terminals. Burst mode is far less efficient than normal operation, and therefore, when the power supply is in standby mode, the secondary controller U2 may continuously change the bus voltage setpoint to prevent the primary controller U1 from entering burst mode, or to enter burst mode with less regularity.

[0063] Figure 4 illustrates a flowchart of Method 400 for determining the mains power supply voltage and / or frequency from the secondary side of a power supply having a converter that uses a transformer to maintain galvanic isolation between the primary and secondary sides of the power supply. In the example, the converter may be a flyback converter, but any converter utilizing such a transformer (e.g., active clamp forward converter, single switch forward converter, two switch forward converter, push-pull converter, half-bridge converter, full-bridge converter, etc.) may be used. Such a power supply may be power supply 100 shown and described in relation to Figure 1, but this is shown only as an example. The method steps in Figure 4 can be performed by a controller such as the secondary side controller U2. The method steps can be programmed as software or firmware in a non-transient memory and executed by the processor of a microcontroller. However, in some examples, some of the steps can be performed in hardware, or as a combination of hardware, software, and / or firmware.

[0064] In step 402, the voltage across the secondary winding of the transformer is measured over a predetermined period, during which the peak voltage from the period or the frequency of the measured voltage from the period can be determined from the voltage. The secondary winding may be either the secondary winding or an auxiliary winding of the transformer (a transformer may have any number of auxiliary windings). The predetermined period may generally be sufficient to capture half a cycle or the entire cycle of the mains power supply voltage. Since the voltage across the secondary winding represents only the mains power supply voltage when the converter is in the forward phase, it can be measured in combination with a peak detector that detects the envelope of the voltage. Any suitable peak detector may be used.

[0065] In step 404, it is determined whether the primary side controller (e.g., primary side controller U1) is operating in burst mode. In the example, the primary side controller is a PFC controller, which is an integrated circuit designed to operate a converter such as a flyback converter. In the example, to determine whether the primary side controller is operating in burst mode, the measured voltage or frequency of the secondary side winding is compared to a threshold. If the measured voltage or frequency is less than the threshold, the primary side controller can be determined to be operating in burst mode; otherwise, the primary side controller can be determined to be operating in standard mode.

[0066] In step 406, if the primary side controller is determined to be in standard mode, the measured voltage and / or frequency of the secondary side winding are supplied as diagnostic information to a remote computing device such as a mobile device or computer. In one example, the measured voltage and / or frequency may be stored in the memory of the secondary side controller until the diagnostic information is requested by the remote computing device. The diagnostic information can be transmitted either wired or wirelessly via any suitable protocol such as DALI, Bluetooth, ZigBee, or NFC. In one example, the magnitude of the measured voltage across the secondary side winding is determined by the number of turns of the secondary side winding relative to the number of turns of the primary side winding, and any intervening circuitry between the secondary side winding and the secondary side controller (e.g., a peak detector, a voltage divider, etc.), so the measured voltage can be converted to the mains power voltage according to some proportionality constant. Similarly, the mains power frequency can be determined from the auxiliary winding, either directly (since they may be the same) or through some conversion process, such as multiplication by a proportionality constant.

[0067] In step 408, if it is determined that the primary side controller is operating in burst mode, the primary side controller may be instructed to increase the voltage setpoint of the converter output voltage (bus voltage). This instruction to increase the voltage setpoint can be made, for example, by increasing the error signal fed back to the primary side controller so that the primary side controller increases the output voltage to compensate for the increase in error (and thus enters normal mode). The error signal can be increased, for example, by increasing the reference voltage of the error amplifier, or by increasing the error signal supplied directly from the secondary side controller to the primary side controller (via an optocoupler).

[0068] The primary side controller may be instructed to increase the voltage setpoint in a manner that keeps the primary side controller in standard mode for a sufficient period of time to measure the mains voltage or mains frequency (at least half a cycle or the entire cycle of the mains voltage, respectively). This can be achieved by setting the setpoint increase high enough to ensure that the primary side controller remains in standard mode for the required period. In other examples, the setpoint may increase over time (e.g., over half a cycle or the entire cycle) to ensure that the primary side controller continues to operate in standard mode to meet changing voltage requirements.

[0069] In step 410, the voltage and / or frequency of the secondary winding are measured while the primary side controller is operating in standard mode due to the increase in the voltage output setpoint in step 408. As described in relation to step 402, the secondary winding can be measured in combination with a peak detector.

[0070] In step 412, similar to step 406, the measured voltage and / or frequency of the secondary winding is supplied as diagnostic information to a remote computing device such as a mobile device or computer. Similarly, the measured voltage and / or frequency can be stored in the memory of the secondary controller until the diagnostic information is requested by the remote computing device (thus this step may be performed after step 414 below). The diagnostic information can be transmitted either wired or wirelessly via any suitable protocol such as DALI, Bluetooth, ZigBee, or NFC. In the example, the measured voltage and / or frequency may be converted to the mains voltage and / or frequency according to, for example, some proportionality constant.

[0071] In step 414, the voltage setpoint is returned to the value it was at before the increase in step 408. The voltage setpoint remains at this value until the next instance in which the voltage and / or frequency should be measured while the primary side controller is in burst mode.

[0072] As described above, instead of changing the setpoint to determine the mains voltage, the setpoint can be changed to keep the primary side controller in standard mode operation to improve efficiency while the power supply is in standby mode. This can be achieved by repeating the voltage setpoint increase in step 408 and the voltage setpoint decrease in step 414 in a loop, thus keeping the primary side controller U1 in standard mode operation. During this period, the output stage may be turned off to avoid generating an output signal while the converter is generating a high bus voltage. This can be continued as long as the power supply remains in standby mode.

[0073] The functions described herein, or parts thereof, and various modifications thereof (hereinafter, "functions") may be implemented, at least in part, through computer programs implemented in tangible form on information carriers such as one or more non-temporary machine-readable media or storage devices for execution by computer program products, such as one or more data processing devices, such as programmable processors, computers, multiple computers and / or programmable logical components, or for controlling the operation of the one or more data processing devices.

[0074] Computer programs can be written in any form of programming language, including compiled languages ​​or interpreted languages, and can be deployed as standalone programs or in any form, including modules, components, subroutines, or other constituent units suitable for use in a computing environment. Computer programs can be deployed to run on a single computer, or on multiple computers located in one site or distributed across multiple sites and interconnected by a network.

[0075] The operations related to performing all or part of the functions may be performed by one or more programmable processors that execute one or more computer programs for performing the functions of the calibration process. All or part of the functions may be performed as dedicated logic circuits, such as FPGAs and / or ASICs (Application-Specific Integrated Circuits).

[0076] Processors suitable for executing computer programs include, for example, both general-purpose and dedicated microprocessors, as well as any one or more processors in any type of digital computer. Generally, a processor receives instructions and data from read-only memory, random-access memory, or both. The components of a computer include a processor for executing instructions and one or more memory devices for storing instructions and data.

[0077] While several embodiments of the invention are described and illustrated herein, those skilled in the art will readily envision various other means and / or structures for obtaining one or more of the advantages and / or results and / or functions described herein, and each such variation and / or modification will be considered within the scope of the embodiments of the invention described herein. More generally, those skilled in the art will readily understand that all parameters, dimensions, materials and configurations described herein are intended to be illustrative, and that actual parameters, dimensions, materials and / or configurations will depend on one or more specific applications in which the teachings of the invention are used. Those skilled in the art will recognize, or be able to determine, many equivalents to specific embodiments of the invention described herein, by mere routine experimentation. Therefore, it should be understood that the embodiments described herein are presented only as examples, and embodiments of the invention may be implemented in ways other than those explicitly described and claimed, within the scope of the appended claims and equivalents. The embodiments of the invention in this disclosure cover each individual feature, system, article, material and / or method described herein. Furthermore, any combination of two or more such features, systems, articles, materials, and / or methods is included within the scope of the invention of this disclosure, provided that such features, systems, articles, materials, and / or methods are not contradictory to each other.

Claims

1. It is a power supply that has a secondary side main power supply measurement function. A converter configured to receive an input voltage and supply a converted output voltage, comprising a transformer having a primary winding and a secondary winding, the transformer defining the primary and secondary sides of the power supply, wherein the primary side of the transformer is galvanically isolated from the secondary side, and the converter includes a switch arranged to interrupt or enable the flow of current through the primary winding of the transformer. A primary-side controller configured to operate the converter via a drive signal supplied to the switch, the primary-side controller operating the converter to maintain the converted output voltage at a target setpoint, wherein the converter is operated in burst mode when the resistance of the load connected to the output terminal of the power supply exceeds a threshold, and the converter is operated in standard mode when the resistance of the load is less than the threshold, or when the primary-side controller is operating the converter to increase the converted output voltage, A power supply comprising: a secondary controller configured to determine the peak voltage and / or frequency of the secondary winding over a predetermined period of time; a secondary controller configured to instruct the primary controller to increase a set value so that the primary controller temporarily operates in standard mode to increase the conversion output voltage when the converter is in burst mode; and a secondary controller that determines the peak voltage and / or frequency of the secondary winding while the primary controller is operating the converter in standard mode; The peak voltage and / or frequency are measured, and then the setpoint is increased over a predetermined period of time so that the primary side controller operates the converter in the standard mode for a period of time long enough to instruct the primary side controller to decrease the setpoint. A power supply in which the predetermined period includes at least one half-cycle of a rectified mains power signal in which the peak voltage is taken, or at least one rectified mains power cycle in which at least two zero crossings are detected in the secondary winding of the transformer and the mains power frequency is determined.

2. The power supply according to claim 1, wherein the secondary controller is configured to supply an estimated mains power voltage and / or mains power frequency based on the peak voltage and / or frequency to a remote computing device.

3. The power supply according to claim 1, wherein the secondary controller is configured to instruct the primary controller to increase the set value by changing the error signal supplied to the primary controller.

4. The power supply according to claim 3, further comprising an amplifier configured to generate the error signal, wherein the amplifier receives a first input representing the converted output voltage and a second input which is a reference input, and the secondary controller is configured to change the error signal by adjusting the second input based on the difference between the first input and the second input.

5. The power supply according to claim 1, wherein the converter is a flyback converter.

6. The power supply according to claim 1, wherein the primary side controller is a power factor correction controller.

7. The power supply according to claim 1, wherein the secondary winding is an auxiliary winding.

8. This is a method for measuring the secondary side main power supply of a power supply. A step of determining the peak voltage and / or frequency of the secondary winding of a transformer over a predetermined period of time, wherein the transformer is used in a converter of the power supply, the converter is configured to receive an input voltage and supply a converted output voltage, the transformer defines the primary and secondary sides of the power supply, the primary side is galvanically isolated from the secondary side, the converter further has a switch arranged to interrupt or enable the flow of current through the primary winding of the transformer, and a microcontroller is arranged on the secondary side of the power supply. A step of determining whether a primary-side controller, configured to operate the converter via a drive signal supplied to the switch, is operating in burst mode or standard mode, according to the peak voltage and / or frequency, wherein the primary-side controller operates the converter to maintain the converted output voltage at a target setpoint; The steps include instructing the primary controller to increase the set value so that it temporarily operates in the standard mode to increase the conversion output voltage, A method comprising the step of determining the peak voltage and / or frequency of the secondary winding while the primary side controller is operating the converter in the standard mode, The peak voltage and / or frequency are measured, and then the setpoint is increased over a predetermined period of time so that the primary side controller operates the converter in the standard mode for a period of time long enough to instruct the primary side controller to decrease the setpoint. A method in which the predetermined period includes at least one half-cycle of the rectified mains power signal in which the peak voltage is taken, or at least one rectified mains power cycle in which at least two zero crossings are detected in the secondary winding of the transformer and the mains power frequency is determined.

9. The method according to claim 8, further comprising the step of supplying to a remote computing device an estimated mains power voltage and / or mains power frequency based on the peak voltage and / or frequency of the secondary winding, which is determined while the converter is operating in the standard mode.

10. The method according to claim 8, further comprising the step of instructing the primary side controller to decrease the set value after determining the peak voltage and / or frequency of the secondary side winding.

11. The method according to claim 8, wherein the step of instructing the primary controller to increase the set value includes the step of changing the error signal supplied to the primary controller.

12. The method according to claim 11, wherein the step of changing the error signal includes the step of increasing the reference voltage of an error amplifier, and the error amplifier compares the converted output voltage with the reference voltage.

13. A computer-readable non-temporary medium storing instructions for a processor system to perform the method described in claim 8.

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