Controller for resonant converter

Abstract

A controller for a resonant converter is described. The resonant converter includes: a first switch and a second switch connected in series with each other between a power source and a reference terminal; and a resonant tank electrically connected to the first switch and the second switch, where the resonant tank includes a resonant capacitor. The controller is configured to: receive a measured voltage signal representative of a voltage at a predetermined point in the resonant tank; determining a voltage correction signaling based on a measured current signal, the measured current signal representing a current flowing in the resonant tank; and in response to the measured voltage signal crossing a voltage threshold, changing a state of the first switch and the second switch after applying the voltage correction signaling as an offset to either the measured voltage signal or the voltage threshold.

Description

Technical Field

[0001] The present disclosure relates to controllers and associated methods for resonant converters. Background Art

[0002] There are technical shortcomings in resonant converter delay compensation. Summary of the invention

[0003] According to a first aspect of the present disclosure, a controller for a resonant converter is provided, the resonant converter comprising:

[0004] A first switch and a second switch connected in series with each other between a power source and a reference terminal; and

[0005] a resonant tank electrically connected to the first switch and the second switch, wherein the resonant tank includes a resonant capacitor;

[0006] The controller is configured to:

[0007] receiving a measured voltage signal representative of a voltage at a predetermined point in the resonant tank;

[0008] determining voltage correction signaling based on a measured current signal representing a current flowing in the resonant tank; and

[0009] In response to the measured voltage signal crossing a voltage threshold, the states of the first switch and the second switch are changed after applying voltage correction signaling as an offset to either the measured voltage signal or the voltage threshold.

[0010] In one or more embodiments, the controller is additionally configured to:

[0011] combining voltage correction signaling with a measured voltage signal to provide corrected voltage signaling, wherein the measured voltage signal represents a voltage at a predetermined point in the resonant tank; and

[0012] Any one or both of the following:

[0013] i) in response to the corrected voltage signaling exceeding an upper voltage threshold, opening the first switch and closing the second switch; and

[0014] ii) in response to the corrected voltage signaling falling below a lower voltage threshold, opening the second switch and closing the first switch.

[0015] In one or more embodiments, the controller is configured to:

[0016] receiving a measured current signal; and

[0017] The measured voltage signal is determined by integrating the measured current signal.

[0018] In one or more embodiments, the controller is configured to:

[0019] receiving a measured voltage signal; and

[0020] The measured current signal is determined by calculating the difference of the measured voltage signal.

[0021] In one or more embodiments, the controller is configured to:

[0022] The voltage correction signaling is determined by multiplying the measured current signal by a compensation factor, which is a constant.

[0023] In one or more embodiments, the controller is configured to:

[0024] A value of a compensation factor is determined for multiplying the measured current signal to determine voltage correction signaling.

[0025] In one or more embodiments, the controller is configured to:

[0026] Determine the time error based on:

[0027] The time difference between: i) the measured voltage signal exceeding the upper voltage threshold; and ii) the subsequent opening of the first switch and closing of the second switch; and / or

[0028] The time difference between: i) the measured voltage signal falling below the lower voltage threshold; and ii) the subsequent opening of the second switch and closing of the first switch;

[0029] determining a compensation factor based on the time error; and

[0030] The measured current signal is multiplied by the compensation factor to determine the voltage correction signaling.

[0031] In one or more embodiments, the resonant converter comprises a half-bridge node at a series connection between the first switch and the second switch. The controller may be configured to:

[0032] Determine the time error based on:

[0033] the time difference between: i) the time at which the measured voltage signal exceeds the upper voltage threshold; and ii) the time at which the voltage at the half-bridge node subsequently falls below a level that is half the supply voltage; and / or

[0034] The time difference between: i) the measured voltage signal falling below the lower voltage threshold; and ii) the time at which the voltage at the half-bridge node subsequently exceeds a level that is half the supply voltage.

[0035] In one or more embodiments, the controller is configured to use a constant fixed value (K constant) instead of the measured current signal.

[0036] In one or more embodiments, the controller is configured to:

[0037] storing the value of the current signal measured at the time when the voltage at the half-bridge node crosses half the supply voltage in the previous switching cycle as a sampled current value;

[0038] The sampled current value is multiplied by the compensation factor to determine the voltage correction signaling.

[0039] In one or more embodiments, the controller is configured to:

[0040] filtering the sampled current values ​​at the times when the voltage at the half-bridge node crosses half the supply voltage over a plurality of previous switching cycles to provide an average sampled current value; and

[0041] The average sampled current value is multiplied by the compensation factor to determine the voltage correction signaling.

[0042] In one or more embodiments, the controller is configured to:

[0043] adding voltage correction signaling to the measured voltage signal to provide a high-side corrected voltage signal;

[0044] subtracting voltage correction signaling from the measured voltage signal to provide a low-side corrected voltage signal;

[0045] In response to the high-side corrected voltage signaling exceeding an upper voltage threshold, opening the first switch and closing the second switch; and

[0046] In response to the low-side correction voltage signaling falling below a lower voltage threshold, the second switch is opened and the first switch is closed.

[0047] A method of controlling a resonant converter is also disclosed, wherein the resonant converter comprises:

[0048] A first switch and a second switch connected in series with each other between a power source and a reference terminal; and

[0049] a resonant tank electrically connected to the first switch and the second switch, wherein the resonant tank includes a resonant capacitor;

[0050] The methods include:

[0051] receiving a measured voltage signal representative of a voltage at a predetermined point in the resonant tank;

[0052] determining voltage correction signaling based on a measured current signal representing a current flowing in the resonant tank; and

[0053] In response to the measured voltage signal crossing a voltage threshold, the states of the first switch and the second switch are changed after applying voltage correction signaling as an offset to either the measured voltage signal or the voltage threshold.

[0054] In one or more embodiments, the method further comprises:

[0055] combining voltage correction signaling with a measured voltage signal to provide corrected voltage signaling, wherein the measured voltage signal represents a voltage at a predetermined point in the resonant tank;

[0056] In response to the corrected voltage signaling exceeding an upper voltage threshold, opening the first switch and closing the second switch; and

[0057] In response to the corrected voltage signaling falling below a lower voltage threshold, the second switch is opened and the first switch is closed.

[0058] Although the present disclosure allows various modifications and alternative forms, the details have been shown in the drawings by way of example and will be described in detail. However, it should be understood that other embodiments other than the described specific embodiments are also possible. All modifications, equivalents and alternative embodiments falling within the spirit and scope of the appended claims are also encompassed.

[0059] The above discussion is not intended to represent every example embodiment or every implementation within the scope of the current or future technical solution set. The drawings and the following detailed description also illustrate various example embodiments. The various example embodiments can be more fully understood by considering the following detailed description in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] One or more embodiments will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0061] Figure 1a A resonant converter and a controller for a resonant converter are shown, which illustrate the principle of Vcap control;

[0062] Figure 1b Show Figure 1a Various signals in the circuit, which also shows the principle of Vcap control;

[0063] Figure 2 An example is shown in which a resonant converter controller includes a pin for receiving a measured current signal;

[0064] Figure 3 Another example of a controller for a resonant converter is shown;

[0065] Figure 4 A block diagram showing an ideal system for compensating for delay;

[0066] Figure 5 An example embodiment of a controller for a resonant converter according to the present disclosure is shown;

[0067] Figure 6 The basic circuit of a controller for performing delay compensation according to one aspect of the present disclosure is shown;

[0068] Figure 7 A curve of the required K (on the vertical axis) versus the signal input frequency (on the horizontal axis) for a 150 ns delay compensation is shown;

[0069] Figure 8 A diagram showing how the voltage changes between: the moment (t1) when the corrected voltage signaling (Vcap_corr) exceeds the upper voltage threshold; and the moment (t2) when the states of the first switch and the second switch change;

[0070] Fig. 9 An adjustment loop for delay compensation is shown;

[0071] Fig.10 An example of how the time error of the loop can be measured is shown;

[0072] Fig.11 Another example embodiment of a controller according to the present disclosure is shown;

[0073] Fig.12 Shows the relationship with Fig.11 Curves of various signals associated with the controller are shown;

[0074] Fig.13 Another example embodiment of a controller according to the present disclosure is shown; and

[0075] Fig.14 A method of controlling a resonant converter according to one aspect of the present disclosure is shown. Detailed Description

[0076] Figure 1a A resonant converter 100 and a controller 101 for the resonant converter 100 are shown, which illustrate the principle of Vcap control. Figure 1b Shows Figure 1a Various signals in the circuit of, which also illustrate the principle of Vcap control.

[0077] As is known in the art, a resonant converter is used to supply electrical energy from a power source 104 to a load. The resonant converter 100 includes a first switch 102 and a second switch 103. The first switch 102 and the second switch 103 are connected in series with each other between the power source 104 and a reference terminal 105. In this example, the reference terminal 105 is grounded. The resonant converter includes a half-bridge node at the series connection between the first switch 102 and the second switch 103. When the first switch 102 is closed and the second switch 103 is open, the resonant converter 100 has a high-side switching half cycle. When the first switch 102 is open and the second switch 103 is closed, the resonant converter 100 has a low-side switching half cycle.

[0078] The resonant converter 100 also has a resonant tank electrically connected to the first switch 102 and the second switch 103. In this example, the resonant tank includes the primary side of a transformer 106 and a resonant capacitor 107.

[0079] Control of the first switch 102 and the second switch 103 is performed via Vcap control, and the voltage across the resonant capacitor 107 is thus measured. The primary current of the resonant converter 100 may also be measured to implement some functionality, which is described below. As will be discussed below, the measured voltage and the measured current may be combined to provide opportunities for delay compensation and better power definition.

[0080] like Figure 1a As shown, the voltage across the resonant capacitor 107 is measured and compared with the controller 101 (which is Figure 1a The levels in the integrated circuit (IC) are shown for comparison. Figure 1b : In response to the voltage (V SNSCAP ) exceeds the upper voltage threshold (V hs(SNSCAP) ), the first switch 102 is opened and the second switch 103 is closed; and in response to the voltage (V SNSCAP ) drops below the lower voltage threshold (V ls(SNSCAP) ), the second switch 103 is opened and the first switch 102 is closed.

[0081] As indicated above, in addition to Vcap control, the primary current of the resonant converter may also be monitored to implement one or more of the following:

[0082] ●Startup function: At startup, when the system slowly increases V hs(SNSCAP) Level and V ls(SNSCAP) The IC can continuously monitor the primary current when the difference between the Vcap levels exceeds a predefined level. When this current exceeds a predefined level, the increase in the difference in Vcap levels can be maintained until the current drops below the predefined level.

[0083] ● To operate the system near capacitive mode (CMR mode), the primary current can be measured. (As is known in the art, when V hs(SNSCAP) Level and V ls(SNSCAP) This results in a larger resonant amplitude as the difference between the levels (sometimes referred to as ΔV) increases. However, the larger amplitude also causes the resonant current to become closer to zero at the end of each half cycle. If the moment when the resonant current becomes zero coincides with the completion of a half cycle, this is called a capacitive mode boundary.)

[0084] ●Overcurrent protection.

[0085] Figure 1a and 1b 1 shows a double-sided vcap control known in the art. One or more examples disclosed herein may also be used with half-cycle control. With half-cycle control, the voltage across the resonant capacitor is measured at the beginning of a switching cycle, and then when the voltage across the capacitor changes by a threshold amount (which may be referred to as ΔVcap), a switching operation is triggered (thus ending the first half of the switching cycle). The second half of the switching cycle is then given the same duration as the first half.

[0086] Figure 2 An example is shown in which the resonant converter controller 201 includes a pin 208 that receives a measured current signal (SNSCUR) that represents the current flowing through the resonant tank of the resonant converter. This pin 208 may be referred to as a snscur pin (where snscur represents sensed current). The controller 201 may integrate the current signal (SNSCUR) received at the snscur pin 208 to reconstruct the measured voltage signal (Vcap) 209. This is because the voltage signal (Vcap) 209 is the integral of the current signal (SNSCUR).

[0087] Figure 3 Another example of a controller 301 for a resonant converter is shown.

[0088] exist Figure 3 In the embodiment of the present invention, the primary current (Ires) is measured across a sense resistor (Rs) in parallel with the main resonant capacitor (Cr) 307. This is done to avoid significant power dissipation in the sense resistor (Rs). However, the disadvantage is that it causes a delay in the feedback path because the component that passes the primary current (Ires) to the measured current signal (SNSCUR) received at the snscur pin 308 of the controller 301 acts as a low pass filter.

[0089] Additional delays may be introduced within the controller 301 by the internal comparator (SNSCAP sense) 310, control logic 311, and driver stage 312. Furthermore, any additional filtering used to reduce noise sensitivity may also increase the overall delay.

[0090] When the effective voltage signal (Vsnscap) across the resonant capacitor 307 at the switching moment is greater than the upper and lower thresholds (V hs(SNSCAP) and V ls(SNSCAP) ), the delay causes an overshoot. This overshoot can be solved by adjusting V in the opposite direction. hs(SNSCAP) and V ls(SNSCAP) value for internal compensation.

[0091] Upper and lower voltage thresholds (V hs(SNSCAP) and V ls(SNSCAP) There is a direct relationship between the delay and the output power of the resonant converter. Therefore, uncompensated delay causes a shift in the output power due to incorrect levels for burst mode transitions, operating modes, and protection. If the delay is too large, the system (e.g., symmetric loop, voltage loop, cycle by cycle) may also become unstable.

[0092] Figure 4 A block diagram of an ideal system for compensating for the delays discussed above is shown.

[0093] Assuming a first order linear input signal, the delay can be compensated by adding the derivative to the signal, multiplying by the delay time.

[0094]

[0095] For a resonant power converter where both the resonant voltage and the primary current are available, the derivative of the voltage signal is available via the primary current (since the primary current is the derivative of the resonant voltage).

[0096] Figure 5 An example embodiment of a controller 501 for a resonant converter 500 according to the present disclosure is shown. Figure 5 The controller 501 implements Figure 4 Delay compensation.

[0097] exist Figure 5In the example of , the controller 501 has a pin 508 for receiving a measured current signal (SNSCUR). The measured current signal (SNSCUR) represents the current flowing in the resonant tank. As will be discussed below, the controller 501 then determines a measured voltage signal (Vcap) 509 based on the measured current signal (SNSCUR). The measured voltage signal (Vcap) represents the voltage at a predetermined point in the resonant tank; in this example, the voltage across the resonant capacitor 507. In other examples, the controller can receive the measured voltage signal (Vcap) and use the measured voltage signal to determine the measured current signal (SNSCUR). For example, the controller can determine the measured current signal (SNSCUR) by calculating the difference of the measured voltage signal (Vcap). However, compared with the example of integrating the measured current signal (SNSCUR), such examples may be more susceptible to noise. In other examples, the controller can receive both the measured voltage signal (Vcap) and the measured current signal (SNSCUR), but in such examples, the controller can have two pins-one pin for receiving each of the measured signals.

[0098] Figure 5 The controller 501 includes an integrator 514 that integrates the received measured current signal (SNSCUR) to determine a measured voltage signal (Vcap) 509 .

[0099] The controller 501 also includes an amplifier 515 that provides a voltage correction signal (dV) 517 based on the measured current signal (SNSCUR). In this example, the amplifier 515 multiplies the measured current signal (SNSCUR) by a compensation factor K, which is a constant in this example. Figure 5 The 'K' in Figure 4 ) In other examples, as will be discussed below, a variable (optionally, via a loop) compensation factor may be used instead of a constant.

[0100] The controller 504 then combines the voltage correction signaling (dV) 517 with the measured voltage signal (Vcap) 509 to provide a corrected voltage signaling (Vcap_corr) 518 . Figure 5 The controller 501 includes an adder 516 that adds a voltage correction signal (dV) 517 to the measured voltage signal (Vcap) 509 to provide a corrected voltage signal (Vcap_corr) 518 .

[0101] The controller 501 then uses the corrected voltage signal (Vcap_corr) 518 for Vcap control. That is:

[0102] In response to the corrected voltage signaling (Vcap_corr) 518 exceeding the upper voltage threshold (V hs(SNSCAP) ), the controller 501 opens the first switch 502 and closes the second switch 503; and

[0103] In response to the corrected voltage signaling (Vcap_corr) 518 falling below the lower voltage threshold (V ls(SNSCAP) ), the controller 501 opens the second switch 503 and closes the first switch 502.

[0104] The controller 501 includes two comparators 510 for comparing the corrected voltage signal (Vcap_corr) 518 with upper and lower voltage thresholds (V hs(SNSCAP) 、V ls(SNSCAP) The two comparators 510 provide output signals caph and capl for controlling the states of the first switch 502 and the second switch 503.

[0105] In this example, the voltage correction signaling (dV) 517 is combined with the measured voltage signal (Vcap) 509 to provide a corrected voltage signaling (Vcap_corr) 518. In an alternative example, the voltage correction signaling (dV) 517 may be compared to an upper voltage threshold (Vcap_corr) 518 before comparing the measured voltage signal (Vcap) 509 to those corrected thresholds. hs(SNSCAP) ) and the lower voltage threshold (V ls(SNSCAP) That is, it should be understood that any one of the input signals of each of the two comparators 510 can be compensated based on the voltage correction signaling (dV) 517 to achieve the same result.

[0106] voltage correction signaling and a measured voltage signal to provide corrected voltage signaling, wherein the measured voltage signal represents a voltage at a predetermined point in the resonant tank; and

[0107] Any one or both of the following:

[0108] i) in response to the corrected voltage signaling exceeding an upper voltage threshold, opening the first switch and closing the second switch; and

[0109] ii) in response to the corrected voltage signaling falling below a lower voltage threshold, opening the second switch and closing the first switch.

[0110] Figure 6 A basic circuit of a controller for performing delay compensation according to an aspect of the present disclosure is shown. Figure 6 Also in Figure 5Features and components shown in the drawings are given corresponding reference numerals in the 600 series and will not necessarily be described again in detail here.

[0111] As mentioned above Figure 5 As described, the primary current ( Figure 6 I_prim in, Figure 5 SNSCUR) is available and measured. Figure 6 The primary current in is scaled via k0 620. The value used for k0 will depend on how the primary current is measured, which is not important to this disclosure. Integration of the primary current by integrator 614 produces a Vcap voltage 609 that is not delayed compensated. This voltage 609 can be generated internally by integrating the primary current (e.g., Figure 6 Multiplying the compensated primary current by K 615 produces voltage correction signaling (dV) 617, which is a voltage offset for timing correction.

[0112] The compensated delay can be Figure 6 The Laplace transform of the block diagram (ignoring k0) is calculated as:

[0113]

[0114] For delay compensation, only the zero is important, since the pole gives a fixed value of 90 degree phase shift. The compensated delay is generated by taking the argument of the Laplace function. A constant compensation factor K can be derived from the compensated delay.

[0115]

[0116]

[0117] As shown in the figure, the constant compensation factor K depends on the frequency of the signal and the requested delay. By approximation, the tangent function is equal to the input for small inputs, which means that when t comp When it is less than 0.05 / f, K is approximately equal to t comp .

[0118] Figure 7 Shown is a plot of required K (on the vertical axis) versus signal input frequency (on the horizontal axis) for a delay compensation of 150 ns.

[0119] As shown, the required value of K varies significantly depending on the frequency. For high frequency LLC converters (i.e. resonant converters with two inductors and one capacitor in their resonant tank), this effect becomes dominant. Therefore, it is beneficial to vary the value of K depending on the actual frequency of interest. In addition to this, the requested delay compensation (t comp) may change due to temperature effects and or different operating modes of the converter.

[0120] Figure 8 It shows how the current changes between: the time when the corrected voltage signaling (Vcap_corr) exceeds the upper voltage threshold (t1); and the time when the states of the first switch and the second switch change (t2).

[0121] Assume that the dv / dt of the Vcap signal is constant, as shown in the reference Figure 4 As explained above, the delay correction described above works well. Figure 7 As shown, sine wave frequencies below approximately 0.05 / t_comp can be correctly compensated. However, the Vcap signal is not based on a constant dv / dt, and in some examples, the frequency may contain more high-order harmonics. As a result (such as Figure 8 As shown in FIG. 1 , between the moment (t1) when Vcap_corr crosses the corresponding Vcap level, a delay time is still required to reach the actual switching moment (t2) of the Hb node.

[0122] Then using the derivative of Vcap (= resonant current), the dv / dt at t2 is less than the dv / dt at t1. Therefore, this means that the delay correction will be based on the dv / dt at t1, which is larger than the dv / dt at the actual switching moment. In order to make the delay correction more accurate, the delay should be based on the dv / dt value at t2. Otherwise, the result may be an overcompensation of the delay. The amount of overcompensation may depend on how close the system is operated to the capacitive mode boundary. At the capacitive mode boundary, the resonant current is zero at t2, so the dv / dt is zero, while the dv / dt at t1 is significantly greater than 0. Analysis of actual systems shows that in this case, instability may occur when the system approaches capacitive mode.

[0123] Therefore, a more accurate delay correction can be based on the primary current at t2. However, this will lead to causality problems because this current only exists after the decision to change the state of the switch has been made. Therefore, in some examples of the present disclosure, as we will now discuss in more detail, the primary current is sampled at t2 and used as a substitute for the instantaneous current to be added to the Vcap signal in the next switching cycle.

[0124] One or more of the examples disclosed herein may be accomplished by performing a Figure 8 A solution to this problem is provided by sampling the resonant current at time t2 in , and using that information to:

[0125] 1. Based on the Vcap signal, define the time t1, where V hs(SNSCAP)level plus the sampled current (for the high-side switching half cycle); and

[0126] 2. Based on the Vcap signal, define the time t1, where V hl(SNSCAP) level minus the sampled current (for the low-side switching half cycle).

[0127] Additionally, the sampled current can be multiplied by a scaling factor, where the scaling factor is set as the result of the local feedback loop comparing the raw Vcap signal (SNSCAP) crossing Vhs with the actual switching instant of the Vhb node. This scaling factor can then be used as Fig. 9 Alternative K_delay is shown. When the delay correction is set appropriately, the result will be that the original Vcap signal crosses the exact same instant as the Vhs(SNSCAP) and Vhl(SNSCAP) nodes switch, thereby fully compensating for the delay.

[0128] Fig. 9 A regulation loop for delay compensation is shown.

[0129] Fig. 9 The regulation loop of t_compensates adaptively to adjust the compensation factor K. The input is t_delay, which is the application and or internal IC delay to be compensated. The error signal t_error is obtained by determining the difference between t_delay and t_comp. t_comp is the actual compensated delay of the control loop.

[0130] The AC transfer function for delay compensation depends on the frequency of interest and the compensation delay. Assume the frequency is between 10KHz and 1MHz, and the delay is 50ns to 200ns to compensate the AC transfer function is fairly constant between 0.5 and 1 (k_delay). Taking the integral of the time error (t_error) completes the loop for adjusting the value of K. An optional offset compensation (t_offset) can be added, which will not affect the stability of the loop).

[0131] In this way, Fig. 9 The regulation loop can determine the value of the compensation factor (K) (which is related to Figure 6 compared to, Fig. 9 The compensation factor K in is not a constant). Fig. 9 Not shown in FIG, but the controller may then multiply the measured current signal (SNSCUR or I_prim) by a compensation factor (K) to determine the voltage correction signal (Vcap_cor).

[0132] The bandwidth of the loop (f_bandwidth) can be set by the following formula:

[0133]

[0134] In this case, the time error of the loop may be desired and thus may be measured.

[0135] Fig.10 An example is shown on how the time error of a loop can be measured.

[0136] This may involve determining when the primary current is maximum and comparing it to the vcap voltage (power level) at that moment. The vcap voltage at which the primary current is highest corresponds to the actual power of the converter and should correspond to the internal Vhs(snscap) level. Fig.10 A block diagram showing how to measure this error by measuring the time difference between: 1) the voltage on the half-bridge node (Vhb, e.g. Figure 5 ii) is the moment when the bus voltage (Vs) reaches half, and ii) the moment when the uncompensated Vcap voltage reaches the desired level (Vhs(snscap)). If there is no time difference between these moments, the desired result of the uncompensated Vcap voltage crossing Vhs(snscap) at the same moment when the half-bridge nodes are switching has been achieved. When the converter is switching in steady state, the set point to be compensated does not usually change quickly.

[0137] More generally, a controller can:

[0138] The timing error (t_error) is determined based on:

[0139] the time difference between: i) the time at which the measured voltage signal (Vcap) exceeds the upper voltage threshold (Vhs); and ii) the time at which the voltage at the half-bridge node subsequently falls below a level that is half the supply voltage (Vs / 2); and / or

[0140] - The time difference between: i) the measured voltage signal (Vcap) falling below the lower voltage threshold (Vls); and ii) the time when the voltage at the half-bridge node subsequently exceeds a level that is half the supply voltage (Vs / 2).

[0141] However, not all delays can be compensated, as there may be differences in the delays among the comparators. Therefore, an offset can be applied to the error (t_offset, e.g. Fig. 9 shown).

[0142] Fig.11 Another example embodiment of a controller according to the present disclosure is shown. Fig.11 Include reference Figure 8 Functionality of a sampled version of the description. Fig.12 Shown with Fig.11The curves of various signals associated with the controller shown in the earlier figure Fig.11 Features and components have been given corresponding reference numerals in the 1100 series and will not necessarily be described in detail again here.

[0143] Fig.11 A sample and hold circuit 1130 is included. The sample and hold circuit 1130 stores the value of the current signal (I_prim) measured at the moment when the voltage (Vhb) at the half-bridge node in the previous switching cycle crosses half the supply voltage (Vs / 2) as a sampled current value. Fig.11 The controller also includes a multiplication block 1134 that multiplies the sampled current value by a compensation factor (k1) (further details of which will be described below) to determine a voltage correction signal (dV) 1117.

[0144] It is possible that using the sampled current of the previous cycle may lead to instability when applied directly. This may happen if each small change in the current at t2 will give a different sampled value, which is added in the next cycle and thereby introduces again a different switching instant and therefore also a different sampled current. When this mechanism reinforces itself, an unstable positive feedback loop may exist. Therefore, in Fig.11 In the example, an optional IIR (infinite impulse response) low pass filter 1131 is added which filters the output signal from the sample and hold circuit 113. The IIR filter 1131 may have such a small bandwidth that the effect of the changing samples does not unduly affect the voltage correction signaling (dV) 1117 which is added to Vcap 1109 as discussed above, or at least gives such small positive feedback that any disturbance is attenuated with an acceptable attenuation factor.

[0145] In this way, the IIR filter 1131 can filter the sampled current values ​​at the time when the voltage (Vhb) at the half-bridge node crosses half of the supply voltage (Vs / 2) within a plurality of previous switching cycles to provide an average sampled current value. The multiplication block 1134 can then multiply the average sampled current value by the compensation factor (k1) to determine the voltage correction signal (dV) 1117.

[0146] The IIR filter 1131 can be much slower than the converter loop and the offset compensation loop. For example, the sampled value can only be updated once per switching cycle. To ensure the bandwidth of the loop, the IIR low-pass filter 1131 can be updated at the same rate as the sample and hold circuit 1130. The integrator 1133 (corresponding to Fig. 9An integrator 1133 of the integrator 933 in 1133 helps keep the loops appropriately separated from each other. This integrator 1133 acts as the integrating part of the regulator, thereby adapting the multiplication factor k1 for the sampled current. Since this multiplication factor actually sets the amount of delay compensation, it forms a closed loop, resulting in a steady-state situation in which the half-bridge node switches exactly at the moment when the Vcap signal crosses Vhs (or Vls). Fig.11 In FIG. 1 , a signal 1132 labeled Vhb_high is used for this purpose. The Vhb_high signal 1132 is the output signal from a comparator that compares the voltage at the half-bridge node (Vhb) with half the supply voltage (Vs / 2). However, it should be understood that in principle any other signal containing the same information may be used instead. This functionality may improve the stability of the resonant converter when it approaches capacitive mode. It may also reduce the noise sensitivity of the delay compensation.

[0147] In this example, the controller determines the time error (t_error). Fig.11 As shown, the controller determines the time error (t_error) based on the time difference between:

[0148] i) The measured voltage signal (Vcap) 1109 exceeds the upper voltage threshold (V hs(SNSCAP) ), which is in Fig.11 In the figure, the output of comparator 1135 is used to identify the

[0149] ii) the ensuing opening of the first switch and closing of the second switch, which Fig.11 11 is indicated by the output of comparator 1136 which compares the voltage at the half-bridge node (Vhb) crossing half the supply voltage (Vs / 2).

[0150] Alternatively or additionally (but Fig.11 (not shown in the figure), the controller can determine the time error (t_error) based on the time difference between:

[0151] i) The measured voltage signal (Vcap) 1109 drops below the lower voltage threshold (V ls(SNSCAP) );and

[0152] ii) The ensuing opening of the second switch and closing of the first switch.

[0153] The controller may then determine a compensation factor (k1) based on the time error (t_error). As discussed above, multiplication block 1134 multiplies the compensation factor (k1) by the sampled current value or the average sampled current value to provide voltage correction signaling (dV) 1117. Alternatively, Fig.13As shown, multiplication block 1344 may multiply constant K_constant 1343 by compensation factor (k1) to determine voltage correction signaling (dV). K_constant 1343 is a simplified version of the sampled current. Fig.11 The sampled current value of and the average sampled current value represent the measured current signal (I_prim), and thus the multiplication block 1134 can also be viewed as multiplying the measured current signal (I_prim) by the compensation factor (k1).

[0154] exist Fig.11 In the example, the controller performs the following operations on the time error (t_error) to provide a compensation factor (k1):

[0155] Apply a time offset (t_offset) to the time error (t_error). The time offset (t_offset) can be used to account for differences in delay between half cycles. This can be particularly useful in examples where information from 1 half cycle is used and the delay for another half cycle may be different. Using the time offset (t_offset) can more or less compensate;

[0156] · Applying a loop factor (K_t_loop) to the time error (t_error). The loop factor (K_t_loop) may be a constant that sets the desired gain of the delay adjustment loop; and

[0157] • In this example, the time error (t_error) is integrated after both the time offset (t_offset) and the loop factor (K_t_loop) have been applied.

[0158] In other examples, one or more of these operations may be omitted.

[0159] Fig.11 A potential disadvantage of the sample and hold circuit 1130 and the IIR filter 1131 is that in the case of double-sided Vcap control, the compensation (dV) now depends on the polarity of the timing compensation. A solution for double-sided Vcap control is to implement error compensation twice (once for controlling the first switch and once for controlling the second switch) or to compensate for voltage correction signaling (dV) in the opposite direction. The advantage of the second option is that there can be no interference between the two delay compensation loops and it is easy to implement. Fig.11 The functionality includes compensating for voltage correction signaling (dV) in the opposite direction to control the first switch and the second switch, as will now be described.

[0160] Fig.11The controller includes a high-side summing block 1137 that adds the voltage correction signal (dV) 1117 to the measured voltage signal (Vcap) 1109 to provide a high-side correction voltage signal (Vcap_corr_hs) 1139. The controller also includes a low-side summing block 1138 that subtracts the voltage correction signal (dV) 1117 from the measured voltage signal (Vcap) 1109 to provide a low-side correction voltage signal (Vcap_corr_ls) 1140.

[0161] Then, in response to the high-side correction voltage signal (Vcap_corr_hs) 1139 exceeding the upper voltage threshold (V hs(SNSCAP) ), the controller sets the caph signal so that the controller opens the first switch and closes the second switch. Fig.11 The high side comparator 1141 in is implemented.

[0162] In response to the low-side correction voltage signal (Vcap_corr_ls) 1140 falling below the lower voltage threshold (V ls(SNSCAP) ), the controller sets the capl signal so that the controller opens the second switch and closes the first switch. Fig.11 The low-side comparator 1142 in is implemented.

[0163] In other examples, half-cycle control can be used instead of Fig.11 Double-sided Vcap control as shown. In this case, only one of the high-side comparator 1141 and the low-side comparator 1142 will be needed.

[0164] Fig.12 Show Fig.11 It should be understood that the high-side correction voltage signal (Vcap_corr_hs) and the low-side correction voltage signal (Vcap_corr_ls) have been combined into Fig.12 A single representation identified as “Vcap_corr” in FIG.

[0165] Fig.12 It is shown that the correction term appears as a positive constant during the high-side half cycle, and the same but negative value during the low-side half cycle. It can also be seen that the decision to change the state of the first and second switches is made based on Vcap_corr crossing one of the thresholds (Vhs or Vls), and a little later, the moment when the Vcap signal crosses the Vhs or Vls signal happens to be the moment when the voltage at the half-bridge node (Vhb) also crosses Vbus / 2. Due to the difference between the two moments when Vhb switches and crosses Vbus / 2, this means that at Fig.11 , the converter delivers the appropriate power indicated by Vhs, Vls.

[0166] Fig.13 Another example embodiment of a controller according to the present disclosure is shown. Fig.13 The circuit is similar to Fig.11 circuit, but it does not include a sample and hold circuit or an IIR filter.

[0167] Due to Fig.11 The associated local feedback loop adjusts to the appropriate delay correction in the steady-state solution, so it can be asked why the sampled current is needed. However, as shown in Ref. Figure 8 As discussed, t2( Figure 8 The dv / dt at (in) is proportional to the current at t2. Therefore, once settled to the proper scaling factor, when immediately changing to another load with another current at t2, proper delay correction is maintained. In this case, the local feedback loop does not need correction. However, it has been found that it is not necessary to sample the measured current; instead, using a constant fixed value (K_constant) 1343 can work. The local feedback loop can still be adjusted to the proper scaling factor to achieve optimal delay correction. Therefore, in Fig.13 In the example, no need Fig.11 The sample and hold circuit and IIR filter.

[0168] Fig.14 A method for controlling a resonant converter according to one aspect of the present disclosure is shown. As discussed in detail above, the resonant converter includes: a first switch and a second switch connected in series with each other between a power supply and a reference terminal; and a resonant tank electrically connected to the first switch and the second switch. The resonant tank includes a resonant capacitor.

[0169] At step 1451, the method comprises determining voltage correction signaling (dV) based on a measured current signal representing the current flowing in the resonant tank. This may be measured directly from the resonant converter, or may be determined based on a different measured signal.

[0170] At step 1452, the method involves combining voltage correction signaling (dV) with the measured voltage signal (Vcap) to provide corrected voltage signaling. The measured voltage signal (Vcap) represents the voltage at a predetermined point in the resonant tank. This can be measured directly from the resonant converter, or can be determined based on different measured signals. As discussed above, the corrected voltage signaling can be a single signal (Vcap_corr). Alternatively, the corrected voltage signaling can include a signal pair (Vcap_corr_ls and Vcap_corr_hs).

[0171] At step 1453 , in response to the corrected voltage signaling exceeding the upper voltage threshold (Vhs), the method involves opening the first switch and closing the second switch.

[0172] At step 1454, in response to the corrected voltage signaling falling below a lower voltage threshold (Vls), the method involves opening the second switch and closing the first switch.

[0173] One or more of the applications described herein may be used in any application using a resonant converter. This includes but is not limited to:

[0174] Adapter

[0175] ●TV

[0176] Games

[0177] Lighting equipment

[0178] ●Car.

[0179] The present disclosure relates to one or more of the following:

[0180] 1. A resonant power converter using Vcap control and where delays are compensated via the primary current signal, resulting in correct power measurements.

[0181] 2. Compensation can be fixed, or adjusted via an internal or external loop.

[0182] 3. Compensation is constant based, where the scaling factor used is set by local feedback.

[0183] 4. The primary current is sampled at the crossing of Vcaprecon and vcap levels (Vhs or Vls) and used to set the second part of the scaling factor ( Figure 8 ).

[0184] 5. The delay can be measured when the HB node changes polarity or via any other method that produces the same result.

[0185] 6. Filtering can be applied to the primary current signal to avoid interfering with other loops.

[0186] 7. Delay compensation can be accomplished through dual Vcap control.

[0187] 8. Delay compensation can be accomplished using single-sided Vcap control.

[0188] 9. Vcap can be an external pin or via internal integration of the primary current signal.

[0189] 10. Because Vcap control is used, all modes associated with this control mechanism can still be used.

[0190] 11. The converter may be an LLC converter.

[0191] 12. The converter can be another type of resonant converter that supports Vcap control.

[0192] 13. The converter may be a half-bridge converter.

[0193] 14. The converter may be a full-bridge converter.

[0194] Examples disclosed herein may include one or more of the following features:

[0195] ● Compensate for delay based on the derivative of the Vsnscap signal to perform correct power measurements and ensure loop stability.

[0196] ●Use the resonant current as a representation of the derivative of the Vsnscap signal.

[0197] ●Adjust delay compensation according to actual delay error.

[0198] ●Filtering to avoid interference with other loops.

[0199] ●Use the Vs / 2 crossing as an indication of the effective Vcap level.

[0200] • Use a sampled version of the resonant current as a representation of the derivative of the Vsnscap signal.

[0201] ●Use the constant of the resonant current as a representation of the derivative of the Vsnscap signal.

[0202] In the control of the resonant power converter, a control method using the voltage across the resonant capacitor can be used. In addition, the resonant current can be measured so that the converter can operate near the capacitive mode, or the current in the converter can be limited. The presence of delay leads to power measurement errors and therefore incorrect power operating thresholds. The examples disclosed herein can solve the problem of delay in power measurement by using the voltage on the resonant capacitor and the current through the resonant capacitor.

[0203] Unless a specific order is explicitly stated, the instructions and / or flow chart steps in the above figures may be executed in any order. Moreover, those skilled in the art will recognize that although an example instruction set / method has been discussed, the materials in this specification may be combined in a variety of ways to produce other examples and should be understood within the context provided in this detailed description.

[0204] In some example embodiments, the instruction set / method steps described above are implemented as functions and software instructions embodied as an executable instruction set, which is implemented on a computer or a machine programmed and controlled with the executable instructions. Such instructions are loaded for execution on a processor (e.g., one or more CPUs). The term processor includes a microprocessor, a microcontroller, a processor module or subsystem (including one or more microprocessors or microcontrollers), or other control or computing devices. A processor may refer to a single component or multiple components.

[0205] In other examples, the instruction sets / methods shown herein and the data and instructions associated therewith are stored in corresponding storage devices, which are implemented as one or more non-transitory machine or computer readable or computer usable storage media. Such computer readable or computer usable storage media are considered to be part of an article (or product). An article or product may refer to any manufactured single component or multiple components. A non-transitory machine or computer usable medium as defined herein does not include signals, but such a medium may be capable of receiving and processing information from signals and / or other transient media.

[0206] Example embodiments of the materials discussed in this specification may be implemented in whole or in part via a network, computer or data-based device and / or service. These may include the cloud, the Internet, an intranet, a mobile device, a desktop computer, a processor, a lookup table, a microcontroller, a consumer device, an infrastructure, or other enabling devices and services. As may be used herein and in the claims, the following non-exclusive definitions are provided.

[0207] In one example, one or more instructions or steps discussed herein are automated. The term automation or automatic (and similar variations thereof) means the use of computers and / or mechanical / electrical devices to control the operation of equipment, systems and / or processes without the need for human intervention, observation, effort and / or decision making.

[0208] It should be understood that any components that are said to be coupled may be coupled or connected directly or indirectly. In the case of indirect coupling, additional components may be located between the two components that are said to be coupled.

[0209] In this specification, example embodiments have been presented according to a selected set of details. However, one of ordinary skill in the art will appreciate that many other example embodiments including different selected sets of these details may be practiced. It is intended that the appended claims cover all possible example embodiments.

Claims

1. A controller for a resonant converter, characterized in that: The resonant converter comprises: A first switch and a second switch connected in series with each other between a power source and a reference terminal; and a resonant tank electrically connected to the first switch and the second switch, wherein the resonant tank includes a resonant capacitor; The controller is configured to: receiving a measured voltage signal representative of a voltage at a predetermined point in the resonant tank; determining voltage correction signaling based on a measured current signal representing a current flowing in the resonant tank; and In response to the measured voltage signal crossing a voltage threshold, the states of the first switch and the second switch are changed after applying the voltage correction signal as an offset to either the measured voltage signal or the voltage threshold.

2. The controller according to claim 1, characterized in that: Additionally configured as: combining the voltage correction signaling with a measured voltage signal to provide corrected voltage signaling, wherein the measured voltage signal represents a voltage at a predetermined point in the resonant tank; as well as Any one or both of the following: i) in response to the corrected voltage signaling exceeding an upper voltage threshold, opening the first switch and closing the second switch; as well as ii) in response to the corrected voltage signaling falling below a lower voltage threshold, opening the second switch and closing the first switch.

3. The controller according to claim 1 or claim 2, characterized in that: The controller is configured to: receiving the measured current signal; and The measured voltage signal is determined by integrating the measured current signal.

4. The controller according to claim 1 or claim 2, characterized in that: The controller is configured to: receiving the measured voltage signal; and The measured current signal is determined by calculating a difference of the measured voltage signal.

5. A controller according to any preceding claim, characterised in that The controller is configured to: The voltage correction signaling is determined by multiplying the measured current signal by a compensation factor, the compensation factor being a constant.

6. The controller according to any one of claims 1 to 4, characterized in that: The controller is configured to: A value of a compensation factor is determined for multiplying the measured current signal to determine the voltage correction signaling.

7. A controller according to claim 6, when dependent on claim 2, characterized in that The controller is configured to: Determine the time error based on: The time difference between: i) the measured voltage signal exceeding the upper voltage threshold; and ii) the subsequent opening of the first switch and the closing of the second switch; and / or The time difference between: i) the measured voltage signal falling below the lower voltage threshold; and ii) the consequent opening of the second switch and the closing of the first switch; determining a compensation factor based on the time error; as well as The measured current signal is multiplied by the compensation factor to determine the voltage correction signaling.

8. The controller according to claim 7, characterized in that: The resonant converter comprises a half-bridge node located at a series connection between the first switch and the second switch; The controller is configured to: The time error is determined based on: the time difference between: i) the time at which the measured voltage signal exceeds the upper voltage threshold; and ii) the time at which the voltage at the half-bridge node subsequently falls below a level that is half the supply voltage; and / or The time difference between: i) the measured voltage signal falling below the lower voltage threshold; and ii) the time at which the voltage at the half-bridge node subsequently exceeds a level that is half the supply voltage.

9. A controller according to any preceding claim, characterised in that Configured to: A constant fixed value is used instead of the measured current signal.

10. A method for controlling a resonant converter, characterized in that: The resonant converter comprises: A first switch and a second switch connected in series with each other between a power source and a reference terminal; and a resonant tank electrically connected to the first switch and the second switch, wherein the resonant tank includes a resonant capacitor; The methods include: receiving a measured voltage signal representative of a voltage at a predetermined point in the resonant tank; determining voltage correction signaling based on a measured current signal representing a current flowing in the resonant tank; and In response to the measured voltage signal crossing a voltage threshold, the states of the first switch and the second switch are changed after applying the voltage correction signal as an offset to either the measured voltage signal or the voltage threshold.

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