Control circuit for power converter with adaptive error signal compensation

Abstract

Described herein is a control circuit (200) for controlling a power converter (100) configured to provide an output current (104) at an output voltage (103) at an output node of the power converter (100) based on electrical power at an input voltage (102) provided at an input node of the power converter (100). The control circuit (200) is configured to determine a voltage error signal (215, 315) based on the output voltage (103) and based on a reference voltage (211) for the output voltage (103); determining an operating point at which the power converter (100) operates within the operating range; offsetting the voltage error signal (215, 315) with an offset (310) dependent on an operating point at which the power converter (100) is operating to determine a compensated voltage error signal (415); and determining a control signal (217) for controlling one or more power switches (111, 112, 113, 114) of the power converter (100) from the compensated voltage error signal (415).

Description

Technical Field

[0001] The present invention relates to a control circuit for a power converter, in particular a buck-boost power converter. In particular, the present invention relates to providing reliable regulation of the output voltage of the power converter over the entire operating range of the power converter. Background Art

[0002] Battery-powered portable devices are increasingly demanding performance, especially in terms of load current and operating efficiency. In applications where the input voltage is always higher than the output voltage, a buck power converter can be used. For applications where the input voltage is always lower than the output voltage, a boost power converter can be used.

[0003] In battery-powered devices, the input voltage is provided by the battery cells. Therefore, the input voltage may vary relatively widely because the voltage of the battery cells depends on their state of charge. Since the voltage of the battery cells decreases as they discharge, the input voltage of the power converter may be higher, approximately equal to, or lower than the output voltage. For this situation, a buck-boost power converter can be used, where the buck-boost power converter has three main operating modes:

[0004] Buck mode → V IN >V OUT

[0005] Buck-boost mode → V IN ~V OUT

[0006] Boost mode → V IN <V OUT

[0007] Figure 1a An example buck-boost power converter 100 is shown, which is configured to convert an input voltage 102 into an output voltage 103 while providing a specific output or load current 104. The power converter 100 includes a control unit 101 for controlling power switches 111, 112, 113, 114 (e.g., field effect transistors) of the power converter 110. The power converter 100 can operate in a specific operating mode, particularly a buck mode, a buck-boost mode, or a boost mode, depending on the conversion ratio between the input voltage and the output voltage. Each operating mode includes a series of states of the power converter 100 within a working cycle. The working cycle (i.e., the state sequence) is repeated at a predetermined cycle rate. In each working cycle, the inductor 115 is magnetized and demagnetized, thereby providing a specific average output or load current 104 at the output of the power converter 100.

[0008] When switching between different operating modes, especially between the buck mode and the buck-boost mode, or between the buck-boost mode and the boost mode, glitches of the output voltage 103 may occur. In addition, the regulation accuracy of the output voltage 103 may depend on the operating mode and / or the conversion ratio and / or the output voltage 103 of the power converter 100.

[0009] The technical problem of providing an accurate regulation of the output voltage 103 of a buck-boost power converter 100 over the entire operating range is solved herein. The technical problem is solved by the independent claims. Preferred examples are described in the dependent claims. Summary of the invention

[0010] According to one aspect, a control circuit for controlling a power converter, in particular a buck-boost power converter, is described. The power converter is configured to provide an output current at an output voltage at an output node of the power converter based on electrical power at an input voltage provided at an input node of the power converter.

[0011] The control circuit is configured to determine a voltage error signal based on the output voltage and based on a reference voltage of the output voltage, wherein the voltage error signal may present a slope within an operating range of the power converter. In addition, the control circuit is configured to determine an operating point within the operating range and to adjust (particularly offset) the voltage error signal using an offset depending on the operating point at which the power converter operates to determine a compensated voltage error signal. The offset (depending on the operating point) may cause the amplitude of the slope of the compensated voltage error signal to be less than the amplitude of the slope of the voltage error signal. In addition, the control circuit is configured to determine a control signal for controlling one or more power switches of the power converter based on the compensated voltage error signal.

[0012] According to another aspect, a method for controlling a power converter, in particular a buck-boost power converter, is described. The method comprises determining a voltage error signal based on an output voltage and based on a reference voltage for the output voltage. Furthermore, the method comprises determining an operating point within the operating range, and adjusting (in particular offsetting) the voltage error signal by an offset depending on the operating point at which the power converter operates, to determine a compensated voltage error signal. The method also comprises determining a control signal for controlling one or more power switches of the power converter based on the compensated voltage error signal.

[0013] According to another aspect, a software program is described. The software program may be suitable for execution on a processor and when executed on the processor performs the method steps outlined herein.

[0014] According to another aspect, a storage medium is described. The storage medium may include a software program adapted to be executed on a processor and which, when executed on the processor, performs the method steps outlined herein.

[0015] According to another aspect, a computer program product is described. The computer program may comprise executable instructions for performing the method steps outlined herein when executed on a computer.

[0016] It should be noted that the methods and systems including the preferred embodiments thereof outlined herein can be used alone or in combination with other methods and systems disclosed herein. In addition, the features outlined in the context of the system also apply to the corresponding method. Furthermore, all aspects of the methods and systems outlined herein can be combined arbitrarily. In particular, the features of the claims can be combined with each other in any manner. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention is explained below in an exemplary manner with reference to the accompanying drawings, in which

[0018] Figure 1a The example shows a buck-boost converter;

[0019] Figure 1b The example shows Figure 1a The inductor current and load current of the power converter in different working modes;

[0020] Figure 2a The example shows a control circuit for controlling the duty cycle of a buck-boost converter;

[0021] Figure 2b The example shows the glitches of the voltage error signal during mode transitions;

[0022] Figure 3a The example shows a control circuit including an error voltage compensation unit;

[0023] Figure 3b shows the error voltage of the control circuit in different working modes;

[0024] Figure 4 showing an error voltage with a decreasing slope, in particular an error voltage with a slope of zero; and

[0025] Figure 5 A flow chart of an example method for controlling a buck-boost power converter is shown. DETAILED DESCRIPTION

[0026] As mentioned above, the present invention aims to provide accurate regulation of the output voltage of the power converter 100, in particular the buck-boost power converter 100, within different operating modes and / or for a wide range of conversion ratios. Figure 1b The waveforms of the inductor current 105 through the inductor 115 for different operating modes, in particular for the buck mode (upper figure), the boost mode (middle figure) and the buck-boost mode (lower figure) are shown. In addition, Figure 1b An output and / or load current 104 provided at the output of the power converter 100 is shown. In addition, Figure 1b The duration T of the working cycle 120 of each working mode is shown. s In addition, the extended time T used in buck-boost mode is shown. ext .

[0027] Depending on the operating mode, the same duty cycle corresponds to different currents 104 delivered to the output of power converter 100. In particular,

[0028] For buck mode

[0029] L,BUCK >=i Load ,

[0030] For boost mode

[0031] as well as

[0032] For Buck-Boost Mode

[0033]

[0034] Therefore, voltage glitches may be generated when the power converter 100 switches between two different operating modes.

[0035] Figure 2a An example control circuit 200 is shown for controlling a buck-boost power converter 100, in particular for setting a duty cycle of the buck-boost power converter 100 within an operating mode of the power converter 100. The control circuit 200 comprises a feedback unit 201, which is configured to generate a feedback voltage 212 based on an output voltage 103 of the power converter 100. Furthermore, the control circuit 200 comprises a reference unit 202, which is configured to provide a reference voltage 211 for the output voltage 103.

[0036] ​The feedback voltage 212 may be compared with the reference voltage 211 in the comparison unit 203 to provide an incremental signal 213 (particularly an incremental current or an incremental voltage) indicating the deviation of the feedback voltage 212 from the reference voltage 211. The incremental signal 213 may be offset using the offset unit 204 to provide a corrected incremental signal 214, which may be amplified in the amplification unit 205 (e.g., in a current mirror or a voltage multiplier) to provide an error voltage 215.

[0037] The error voltage 215 may be compared with a (sawtooth) ramp voltage 216 (including a (sawtooth) ramp having a periodicity corresponding to the duration of the operation cycle 120) which may be provided by the ramp signal unit 206. The ramp voltage 216 may be generated according to the inductor current 105, in particular according to the peak value of the inductor current 105.

[0038] The error voltage 215 and the ramp voltage 216 may be compared within a PWM (pulse width modulation) comparator unit 207 to provide a control signal 217 for the power switches 111, 112, 113, 114 of the power converter 100. The control signal 217 may indicate a duty cycle for operating the power converter 100. The control unit 101 may use the control signal 217 to generate a drive signal for controlling the power switches 111, 112, 113, 114.

[0039] When using peak current based control, the following equation applies:

[0040] [V DAC -(V OUT / FB ratio )]×g mLOOP =I L / N S +I slopeComp

[0041] Where V DAC is the reference voltage 211, V OUT / FB ratio is the feedback voltage 212, g mLOOP is the gain applied by the control circuit 200 when generating the error voltage 215. L is the inductor current 105, N S is the gain applied to the inductor current 105, and I slopeComp It is the slope compensation applied in the context of current based control (within the ramp signal unit 206).

[0042] like Figure 2b As shown, the above control scheme leads to V errorSignal 215 is discontinuous at the mode transition boundaries between buck mode, boost mode, and buck-boost mode. These discontinuities can cause glitches in the output voltage. In particular, Figure 2b V across different modes (particularly buck mode 221, buck-boost mode 222, and boost mode 223) is shown. error signal 215. It can be seen that when switching between two different modes 221, 222, 223, V error A glitch 231 of the signal 215 results in a corresponding glitch of the output voltage 103 .

[0043] Therefore, the goal here may be to remove the spurs 231 in the error signal 215 at the mode switching boundaries. In particular, the goal here may be to provide a linear error signal 215 across the switching boundaries regardless of the input and / or output voltage conditions.

[0044] This can be achieved by applying an offset adjusted based on the operating mode within the control circuit 200. The adaptive offset can remove the glitch 231 and can provide a linear error signal 215. In addition, the adaptive offset can remove the corresponding output voltage glitch and can provide an improved output voltage characteristic of the power converter 100.

[0045] As described above, the buck-boost converter 100 can be used in portable devices because the battery voltage depends on the state of charge (the battery voltage decreases as the battery discharges). As a result, the input voltage of the power converter 100 can be higher, approximately equal to, or lower than the desired output voltage. When using peak current-based control, glitches 231 appear on the error signal 215 at the transition boundaries between operating modes (buck mode 221 to buck-boost mode 222, and / or buck-boost mode 222 to boost mode 223). These glitches 231 typically appear on the output voltage 103.

[0046] As outlined herein, an adaptive offset to the error signal 215 may be used that removes the glitch 231 and produces a linear error signal 215. Thus, the output voltage 103 does not exhibit glitches when switching between modes.

[0047] Figure 3a An example control circuit 200 is shown including an adaptive offset and / or compensation unit 300. The compensation unit 300 may be configured to generate a reference signal 310 (i.e., offset), in particular a reference voltage or current, which is configured to adjust the incremental signal 213 in an adaptive manner, in particular to offset the incremental signal 213. Figure 3a The compensation unit 300 shown in FIG. 3 is only one example of generating the reference signal 310 .

[0048] The compensation unit 300 may be configured to generate a reference signal 310 based on the input voltage 102, the output voltage 103, and an indicator 301 indicating a mode transition and / or indicating a currently used operating mode 221, 222, 223. Based on this information, a predetermined mapping unit (e.g., a predetermined lookup table) may be used to determine the value of the reference signal 310 (i.e., the value of the offset).

[0049] The mapping unit may determine as follows (using the power converter 100 preferably integrated within its application),

[0050] For each (V IN ,V OUT ) Yes, I am sure Lpeak and loop error voltage 215.

[0051] Therefore, the function V error =f(V OUT ,V IN ) can be, for example, Figure 2b or Figure 3b Determine as shown in .

[0052] ·from Figure 2b or Figure 3b Starting from point A in , DY1 can be determined, and based on this, parameters a1 and b1 can be determined. These parameters can be used to apply an offset [a1*V OUT +b1].

[0053] In a similar way, from Figure 2b or Figure 3b Starting from point B in , DY2 and parameters a2 and b2 can be determined. These parameters can be used to apply an offset [a2*V OUT +b2].

[0054] Thus, the adaptive offset for the buck-boost mode 222 and / or the boost mode 223 may be determined during a calibration phase of the control circuit 200 and / or the power converter 100. The adaptive offset 310, i.e., the reference signal, may then be applied during operation of the control circuit 200 and / or the power converter 100, thereby providing a compensated incremental signal 314 and a reference signal such as Figure 3b A linear curve of the compensated voltage error signal 315 is shown.

[0055] The reference voltage 310 can be generated by a plurality of selectable current sources (not shown). Depending on the desired correction, an appropriate reference offset voltage 310 is generated. To control the selection, the control circuit 200 can utilize a lookup table (not shown) containing V IN 102. V OUT103 and mode changes or modes 221, 222, 223 (buck to buck / boost and vice versa, from buck / boost to boost and vice versa). Based on V IN and V OUT Input and based on the mode or mode change, the lookup table selects the appropriate current source to provide the desired reference offset voltage 310 to generate the compensated error voltage 315.

[0056] Figure 3b V as a function of the target output voltage and / or as a function of the conversion ratio of the power converter 100 is shown. error Signal, i.e., compensated error voltage 315. It can be seen that even after removing the burr 231, the value of the compensated error voltage 215 depends largely on the target output voltage and / or the conversion ratio. In other words, the compensated error voltage 215 exhibits a slope across the range of the target output voltage and / or the conversion ratio, and the slope is non-zero, in particular negative. This slope can affect the accuracy of adjusting the output voltage 103 to the corresponding target output voltage (i.e., the corresponding reference voltage 211).

[0057] The compensation unit 300 can be configured to generate an adaptive offset 310, i.e., a reference voltage, which is configured to modify the error voltage 215 (particularly the incremental signal 213) so that the magnitude and / or value of the compensated error voltage 315 is substantially independent of the target output voltage and / or conversion ratio (i.e., the operating point of the power converter 100). By doing so, the output voltage 103 can be adjusted in a precise manner over the entire range of target output voltages and / or conversion ratios (i.e., over the entire operating range of the power converter 100).

[0058] Figure 4 The compensated voltage error signal 415 is shown to be substantially constant over the entire range of the target output voltage and / or conversion ratio. This can be achieved by rotating (linearizing) the voltage error signal 315 (eg, Figure 3b 4 (shown), where the rotation point 411 can be placed at a predefined target output voltage and / or conversion ratio 410. During the calibration phase, the offset 310, i.e., the reference voltage, can be determined for different values ​​within the range of the target output voltage and / or conversion ratio (i.e., for different operating points of the power converter 100). The offset 310 can be determined based on the uncompensated voltage error signal 215 so that the compensated voltage error signal 415 (which has been compensated by the offset 310) is substantially constant for different values ​​within the range of the target output voltage and / or conversion ratio. The offset 310 can be stored in a lookup table.

[0059] Therefore, if Figure 3bIn the context of peak current control, V OUT The error signal 215 exhibits a negative slope in buck, buck-boost, and boost modes. In this article, an adaptive offset 310 for the voltage error signal 215 (particularly for the delta signal 213) is used to generate a compensated voltage error signal 315, 415, which exhibits a slope of approximately zero in buck, buck-boost, and boost modes. Therefore, output voltage regulation in all operating modes is improved. The adaptive offset 310 can be generated using a compensation unit 300.

[0060] During the calibration phase, the adaptive offset 310 can be determined for various operating points, in particular for various conversion ratios or for various target output voltages. For a particular operating point, the (possibly linearized) V OUT The difference between the error signal 215, 315 and the target error signal (having a zero slope) can be stored as an adaptive offset 310 for a particular operating point. In a similar manner, the offset 310 can be determined for a plurality of different operating points.

[0061] Alternatively, the adaptive offset 310 may be approximated by a linear function (e.g., a linear function of the target output voltage and / or the conversion ratio). The coefficients of the linear function may be calculated by calculating the (possibly linearized) V OUT The voltage error signal 215 , 315 is determined by the difference between the target voltage error signal (having a zero slope).

[0062] Figure 5 A flow chart of an example (possibly computer-implemented) method 400 for controlling a power converter 100 (particularly a buck-boost power converter 100) is shown, the method 400 being configured to provide an output current 104 at an output voltage 103 at an output node of the power converter 100 based on electrical power at an input voltage 102 provided at an input node of the power converter 100 (e.g., via a battery).

[0063] The method 500 includes determining 501 a voltage error signal 215, 315 based on the output voltage 103 and based on a reference voltage 211 (ie, a target output voltage) of the output voltage 103. The voltage error signal 215, 315 (eg, Figure 3b ) exhibits a (negative) slope within the operating range of the power converter 100. The voltage error signal 215, 315 (as shown in Figure 3b ) as outlined in the context of ) can be linearized to eliminate one or more glitches 231.

[0064] Furthermore, method 500 includes determining 502 an operating point at which power converter 100 operates within the operating range. The operating point may correspond to a specific conversion ratio of power converter 100 and / or a specific target output voltage or reference voltage 211 .

[0065] The method 500 further comprises adjusting (in particular offsetting) 503 the voltage error signal 215, 315 with an offset 310 depending on the operating point at which the power converter 100 is operated, in order to determine a compensated voltage error signal 415. The offset 310 depending on the operating point may be such that the amplitude of the slope of the compensated voltage error signal 415 is smaller than the amplitude of the slope of the (uncompensated) voltage error signal 215. In particular, the offset 310 depending on the operating point may be such that the amplitude of the slope of the compensated voltage error signal 415 is substantially zero (over the entire operating range of the power converter 100). The offset 310 depending on the operating point may have been predetermined in a calibration phase and may have been stored in the memory unit.

[0066] The (uncompensated) voltage error signal 215 is typically a function of the operating point of the power converter 100, in particular its output voltage 103 and / or the reference voltage 211. The function has a slope that may have an (average) amplitude. The voltage error signal 215, 315 may adopt an offset 310, wherein the value of the offset 310 depends on the operating point at which the power converter 100 is operated. In other words, the value of the offset 310 may be a function of the operating point of the power converter 100, in particular its output voltage 103 and / or the reference voltage 211. Typically, the offset 310 has different values ​​for different operating points.

[0067] The offset 310 may be predetermined such that applying the offset 310 to the voltage error signal 215, 315 results in a reduction in the slope (particularly the amplitude of the slope) of the voltage error signal 215, 315. This results in a compensated voltage error signal 415 having a reduced slope, in particular a slope having a reduced amplitude. In a preferred example, the offset 310 is such that the slope of the compensated voltage error signal 415 (over the entire operating range of the power converter 100) is substantially zero, and therefore the value of the compensated voltage error signal 415 is independent of the operating point of the power converter 100, in particular, independent of the output voltage 103 of the power converter 100 and / or the reference voltage 211.

[0068] Furthermore, the method 500 includes determining 504 a control signal 217 for controlling one or more power switches 111 , 112 , 113 , 114 of the power converter 100 based on the compensated voltage error signal 415 .

[0069] Thus, a control circuit 200 for controlling a power converter 100 (particularly a buck-boost power converter 100) is described, wherein the power converter 100 is configured to provide an output current 104 at an output voltage 103 at an output node of the power converter 100 based on electrical power at an input voltage 102 provided at an input node of the power converter 100.

[0070] The control circuit 200 is configured to determine a voltage error signal 215, 315 based on the output voltage 103 and based on a reference voltage 211 of the output voltage 103. In particular, the control circuit 200 may be configured to determine an incremental signal 213 based on the output voltage 103 and based on the reference voltage 211. For this purpose, the control circuit 200 may include a feedback unit 201 configured to generate a feedback voltage 212 based on the output voltage 103. In addition, the control circuit 200 may include a comparison unit 203 configured to compare the feedback voltage 212 with the reference voltage 211 to generate an incremental signal 213. The voltage error signal 215, 315 may be determined based on the incremental signal 213, for example, by an offset and / or scaling operation. In an example, the voltage error signal 215, 315 corresponds to the incremental signal 213.

[0071] The voltage error signal 215, 315 exhibits a (negative) slope over the operating range of the power converter 100. The operating range of the power converter 100 may correspond to a range of values ​​of the reference voltage 211, the span of which spans from a minimum value to a maximum value, and the operating point of the power converter 100 may correspond to a value of the reference voltage 211, which is between the minimum value and the maximum value. Alternatively or additionally, the operating range of the power converter 100 may correspond to a range of values ​​of the conversion ratio between the input voltage 102 and the output voltage 103, the span of which spans from a minimum value to a maximum value, and the operating point of the power converter 100 may correspond to a value of the conversion ratio, which is between the minimum value and the maximum value.

[0072] The operating range of the power converter 100 may span across different operating modes 221 , 222 , 223 of the power converter 100 , in particular across a buck mode 221 , a buck-boost mode 222 and a boost mode 223 .

[0073] The control circuit 200 is further configured to determine an operating point at which the power converter 100 is (currently) operating within the operating range.

[0074] Furthermore, the control circuit 200 is configured to adjust (in particular offset) the voltage error signals 215, 315 with an offset 310 depending on the operating point at which the power converter 100 is operated, in order to determine a compensated voltage error signal 415. The offset 310 depending on the operating point may be such that the amplitude and / or the absolute value of the slope of the compensated voltage error signal 415 is smaller than the amplitude and / or the absolute value of the slope of the (uncompensated) voltage error signal 215, 315. In particular, the offset 310 depending on the operating point may be such that the amplitude and / or the absolute value of the slope of the compensated voltage error signal 415 is substantially zero over the (entire) operating range of the power converter 100, and / or the amplitude and / or the absolute value of the slope of the compensated voltage error signal 415 is 10% or less of the amplitude of the reference voltage 211 over the (entire) operating range of the power converter 100.

[0075] Therefore, the control circuit 200 is configured to apply a (predetermined) operating point-dependent offset 310 to the voltage error signal 215, 315 in order to provide a compensated voltage error signal 415 that is substantially constant over the (entire) operating range of the power converter 100. This enables accurate regulation of the output voltage 103 over the (entire) operating range of the power converter 100.

[0076] The control circuit 200 may also be configured to determine a control signal 217 for controlling one or more power switches 111, 112, 113, 114 of the power converter 100 based on the compensated voltage error signal 415. The control signal 217 may indicate a duty cycle (of one or more power switches 111, 112, 113, 114) within a duty cycle 120 of the operating mode 221, 222, 223 in which the power converter 100 operates.

[0077] The control circuit 200 may be configured to determine the operating point dependent offset 310 from a predetermined lookup table indicating the offset 310 for a plurality of different operating points within the operating range of the power converter 100. Alternatively or additionally, the control circuit 200 may be configured to determine the operating point dependent offset 310 using a predetermined analysis function indicating the offset 310 depending on an operating point within the operating range of the power converter 100.

[0078] The lookup table and / or the analytical function may be determined in the context of a calibration phase and may be stored in a memory unit of the control circuit 200. By using the lookup table and / or by the analytical function, the regulation accuracy of the output voltage 103 may be further improved.

[0079] The control circuit 200 may be configured to select an operating mode 221, 222, 223 in which the power converter 100 operates from a plurality of different operating modes 221, 222, 223. The plurality of operating modes 221, 222, 223 may include a buck mode 221, a buck-boost mode 222, and a boost mode 223. The operating point-related offset 310 may be determined according to the operating modes 221, 222, 223 in which the power converter 100 operates, thereby further improving the regulation accuracy of the output voltage 103.

[0080] The control circuit 200 may include a plurality of current sources, each of which is configured to generate an offset current. Furthermore, the control circuit 200 may be configured to control and / or select one or more of the plurality of current sources according to an offset 310 that depends on the operating point, to adjust (in particular offset) the voltage error signal 215, 315 using the offset current provided by the one or more current sources. By utilizing current sources, the offset 310 may be generated in a particularly efficient and accurate manner.

[0081] The control circuit 200 may be configured to perform current control, in particular peak current control, of the power converter 100. In particular, the control circuit 200 may be configured to generate a (sawtooth) ramp signal 216 according to the inductor current 105 through the inductor 115 of the power converter 100. The compensated voltage error signal 415 may be compared with the ramp signal 216 to generate a control signal 217 in an accurate and robust manner.

[0082] As described above, it may be beneficial to first linearize the voltage error signal 215, 315 (by removing one or more glitches 231 at one or more transitions between different operating modes 221, 222, 223 of the power converter 100) before applying an operating point-dependent offset 310 (to reduce the slope of the voltage error signal 215, 315). In this case, the control circuit 200 may be configured to adjust (in particular offset) the incremental signal 213 according to the operating mode 221, 222, 223 of the power converter 100 to determine the voltage error signal 215, 315.

[0083] The incremental signal 213 may exhibit a glitch 231 at a transition between two different operating modes 221, 222, 223 of the power converter 100. The control circuit 200 may be configured to adjust (particularly offset) the incremental signal 213 so that at a transition between the two different operating modes 221, 222, 223, the magnitude of the glitch 231 of the voltage error signal 215, 315 is smaller than the magnitude of the glitch 231 within the incremental signal 213.

[0084] Therefore, the control circuit 200 may be configured to apply a first offset 310 to the delta signal 213 to determine the voltage error signal 215, 315. The first offset 310 may depend on the operating mode 221, 222, 223 of the power converter 100.

[0085] The control circuit 200 may be configured to use a (predetermined) mapping unit to determine the first offset 310. The mapping unit may indicate a relationship, in particular a functional relationship and / or a lookup table, between the output voltage 103 and the operating modes 221, 222, 223 on one side of the power converter 100 and the corresponding first offset (310) on the other side thereof.

[0086] In a preferred example, the control circuit 200 is configured to use a polynomial function (particularly a function a*V OUT + b) to determine the first offset 310, the polynomial function includes one or more polynomial parameters (particularly a and b), wherein V OUT is the output voltage 103 . One or more polynomial parameters may depend on the operating mode 221 , 222 , 223 of the power converter 100 .

[0087] By applying first offset 310 to incremental signal 213 to remove one or more glitches 231 , the accuracy of voltage regulation may be further improved.

[0088] Furthermore, a power converter 100 , in particular a buck-boost power converter 100 , is described, which comprises a control circuit 200 as described herein.

[0089] It should be noted that the description and the accompanying drawings illustrate only the principles of the proposed method and system. Those skilled in the art will be able to implement various arrangements that embody the principles of the present invention and are included in the spirit and scope of the present application, although not explicitly described or illustrated herein. In addition, all examples and embodiments summarized herein are primarily intended to be clearly used for illustrative purposes only, to help the reader understand the principles of the proposed method and system. In addition, all statements of the principles, aspects and embodiments of the present invention and specific examples thereof provided herein are intended to cover their equivalents.

Claims

1. A control circuit for controlling a power converter, the power converter being configured to provide an output current at an output voltage at an output node of the power converter based on electric power at an input voltage provided at an input node of the power converter; wherein, The control circuit is configured to: - determining a voltage error signal based on the output voltage and on a reference voltage for the output voltage, wherein the voltage error signal exhibits a slope within an operating range of the power converter; - determining an operating point at which the power converter operates within the operating range; - adjusting the voltage error signal by an offset depending on the operating point at which the power converter operates to determine a compensated voltage error signal, wherein the offset is such that the magnitude of the slope of the compensated voltage error signal is less than the magnitude of the slope of the voltage error signal; and - determining a control signal for controlling one or more power switches of the power converter based on the compensated voltage error signal.

2. The control circuit according to claim 1, wherein: The offset makes the amplitude of the slope of the compensated voltage error signal: - is substantially zero within said operating range of said power converter; or - is 10% or less of the magnitude of the reference voltage within the operating range of the power converter.

3. The control circuit according to claim 1, wherein: - the operating range of the power converter corresponds to a range of values ​​of the reference voltage, the range of values ​​spanning from a minimum value to a maximum value; and - said operating point corresponds to a value of said reference voltage between said minimum value and said maximum value; or - the operating range of the power converter corresponds to a range of values ​​of the conversion ratio between the input voltage and the output voltage, the range spanning from a minimum value to a maximum value; and The implemented operating point corresponds to a value of the implemented conversion ratio between said minimum value and said maximum value.

4. The control circuit according to claim 1, wherein: The control circuit is configured to: - determining the offset from a predetermined lookup table, the predetermined lookup table indicating the offset for a plurality of different operating points within the operating range of the power converter; or - determining the offset using a predetermined analysis function, the predetermined analysis function indicating the offset as a function of the operating point within the operating range of the power converter.

5. The control circuit according to claim 1, wherein: The control circuit is configured to: -selecting an operating mode in which the power converter operates from a plurality of different operating modes, wherein the plurality of operating modes include a buck mode, a buck-boost mode and a boost mode; and - The offset is determined according to the operating mode in which the power converter operates.

6. The control circuit according to claim 1, wherein: The control circuit is configured to: - determining an incremental signal based on the output voltage and based on the reference voltage; and - adjusting the increment signal according to the operating mode of the power converter to determine a voltage error signal.

7. The control circuit according to claim 6, wherein: - the incremental signal exhibits glitches when switching between two different operating modes of the power converter; and The control circuit is configured to adjust the incremental signal such that the magnitude of a glitch in the voltage error signal is smaller than the magnitude of a glitch in the incremental signal at a transition between two different operating modes.

8. The control circuit according to claim 6, wherein: The control circuit is configured to apply a first offset to the delta signal to determine the voltage error signal; wherein the first offset depends on the operating mode of the power converter.

9. The control circuit according to claim 8, wherein: - the control circuit is configured to determine the first offset using a mapping unit; and The mapping unit indicates a relationship between the output voltage and the operating mode on one side of the power converter and a corresponding first offset on another side of the power converter.

10. The control circuit according to claim 1, wherein: The control circuit is configured to: - generating a ramp signal according to an inductor current through an inductor of the power converter; and - Comparing the compensated voltage error signal with the ramp signal to generate the control signal.

11. The control circuit according to claim 1, wherein: The control circuit is configured to perform current control of the power converter.

12. The control circuit according to claim 1, wherein: The control signal indicates a duty cycle within a duty cycle of an operating mode in which the power converter operates.

13. A power converter, wherein: - the power converter is configured to provide an output current at an output voltage at an output node of the power converter based on electrical power at an input voltage provided at an input node of the power converter; and - The power converter comprises a control circuit as claimed in claim 1.

14. A method for controlling a power converter, the power converter being configured to provide an output current at an output voltage at an output node of the power converter based on electrical power at an input voltage provided at an input node of the power converter; wherein, The method comprises: determining a voltage error signal based on the output voltage and based on a reference voltage for the output voltage, wherein the voltage error signal exhibits a slope within an operating range of the power converter; determining an operating point at which the power converter operates within the operating range; adjusting the voltage error signal using an offset amount that depends on an operating point at which the power converter operates to determine a compensated voltage error signal, wherein the offset amount causes a magnitude of a slope of the compensated voltage error signal to be less than a magnitude of a slope of the voltage error signal; and A control signal for controlling one or more power switches of the power converter is determined based on the compensated voltage error signal.

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