PWM wave generation device, dcdc converter control device, PWM wave generation method, and dcdc converter control method

Abstract

One embodiment of the present disclosure is provided with a PWM setting unit (203), a random number generation unit (204), a variation amount generation unit (205), an addition unit (206), a counter unit (207), and a comparison unit (208), which generate PWM waves at a fixed cycle, and increase and decrease the ON period of each PWM wave such that the duty ratio of the PWM waves is stored when observed at a control cycle comprising two or more fixed cycles.

Description

Technical Field

[0001] The present disclosure relates to a PWM (Pulse Width Modulation) wave generating device, a DCDC (Direct Current to Direct Current) converter control device, a PWM wave generating method, and a DCDC converter control method. Background Art

[0002] In a vehicle power supply device, a high-precision switching power supply is used, and measures are taken to prevent electromagnetic interference (EMI) from being generated by a large number of electronic devices used in the vehicle.

[0003] In a DCDC converter that adopts a switching method with excellent conversion efficiency, the on / off time ratio (duty ratio) of a semiconductor switch is controlled by a PWM signal to perform voltage step-up and step-down.

[0004] As a method of reducing such switching noise, there is a spread spectrum (hereinafter referred to as "SS") method of varying the switching frequency to disperse the noise energy.

[0005] Conventionally, there is known a technique for reducing harmonic noise by changing the carrier frequency of a PWM wave to perform SS (for example, refer to Patent Document 1).

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2009-296849 Summary of the invention

[0009] Problem that the invention aims to solve

[0010] Device control (for example, switching power supply control including a high-precision DCDC converter) is being performed by accurate duty cycle control, and such hardware PWM control has also been implemented as a dedicated IC for use.

[0011] However, with the electrification and electronicization of vehicles in recent years, flexible software control using a CPU (Central Processing Unit) is also performed in PWM control in order to perform complex control corresponding to driving conditions and usage conditions of equipment in vehicle backup power supplies.

[0012] In embedded software that executes multiple functions / applications / subroutines in real time, if the processing time of each process varies, scheduling becomes complicated.

[0013] When generating PWM waves by software, if the carrier frequency changes, the generation processing time will also change, which may affect the execution time of subroutines of other functions.

[0014] The non-limiting embodiments of the present disclosure help to provide a PWM wave generating device, a DCDC converter control device, a DCDC converter PWM wave generating method, a DCDC converter control method and a program, wherein software control is performed to keep the generation processing time unchanged, maintain the duty cycle of the PWM wave in each control time period, and generate a spread spectrum PWM wave.

[0015] Solutions to the problem

[0016] A PWM wave generating device according to an embodiment of the present disclosure includes:

[0017] A counter circuit that generates a count value that is reset at a certain period;

[0018] A threshold generation circuit that generates an initial threshold;

[0019] a variation generating circuit for generating the variation so that the total of the variation in each control period consisting of two or more of the certain periods becomes 0; and

[0020] The comparison circuit compares the value based on the count value with a threshold value based on the initial threshold value, and generates a PWM wave based on the variation amount.

[0021] A PWM wave generation method according to an embodiment of the present disclosure comprises the following steps:

[0022] Generate a count value that is reset at a certain period;

[0023] Generate initial thresholds;

[0024] generating the variation amount so that the total of the variation amounts in each control period consisting of two or more of the certain periods becomes 0; and

[0025] A value based on the count value is compared with a threshold value based on the initial threshold value, and a PWM wave is generated based on the variation amount.

[0026] In addition, these broad or specific embodiments may be implemented by systems, devices, methods, integrated circuits, computer programs or recording media, or by any combination of systems, devices, methods, integrated circuits, computer programs and recording media.

[0027] Effects of the Invention

[0028] According to an embodiment of the present disclosure, it is possible to improve the spectrum spreading effect while making it easier to maintain the duty ratio of the PWM wave.

[0029] Further advantages and effects in one embodiment of the present disclosure will be clearly presented by the description and the drawings. The above advantages and / or effects are provided by several embodiments and the features described in the description and the drawings, but not necessarily all of them are provided in order to obtain one or more of the same features. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 1 is a diagram showing a configuration of an example of a DCDC converter device according to an embodiment of the present disclosure.

[0031] Figure 2 This is a diagram showing an example of a functional configuration of a CPU according to an embodiment of the present disclosure.

[0032] Figure 3 This is a timing chart showing an example of PWM signal generation according to one embodiment of the present disclosure.

[0033] Figure 4A This is a flowchart showing an example of generating a buck-boost control PWM signal according to one embodiment of the present disclosure.

[0034] Figure 4B This is a flowchart showing an example of generating a buck-boost control PWM signal according to one embodiment of the present disclosure.

[0035] Figure 5 1 is a timing chart showing an example of generating a spread spectrum PWM signal according to an embodiment of the present disclosure.

[0036] Fig. 6A This is a diagram showing an example of a time waveform of a PWM wave according to one embodiment of the present disclosure.

[0037] Figure 6B This is a diagram showing an example of a time waveform of a PWM wave according to one embodiment of the present disclosure.

[0038] Figure 6C This is a diagram showing an example of a frequency spectrum of a PWM wave according to an embodiment of the present disclosure.

[0039] Fig.6D This is a diagram showing an example of a frequency spectrum of a PWM wave according to an embodiment of the present disclosure.

[0040] Figure 7 This is a block diagram showing an example of a random number generation unit according to one embodiment of the present disclosure.

[0041] Figure 8 This is a diagram showing an example of an overlapping variation sequence according to one embodiment of the present disclosure.

[0042] Fig. 9 This is a diagram showing another example of the functional configuration of the CPU according to one embodiment of the present disclosure. DETAILED DESCRIPTION

[0043] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In addition, the embodiments described below are just examples, and the present disclosure is not limited to the following embodiments.

[0044] Hereinafter, the embodiments of the present disclosure will be described in detail with reference to the accompanying drawings as appropriate. However, sometimes an overly detailed description may be omitted. For example, sometimes a detailed description of a well-known matter or a repeated description of a substantially identical structure may be omitted. This is to avoid the following description from becoming unnecessarily lengthy and to make it easy for those skilled in the art to understand.

[0045] In addition, the drawings and the following description are provided for the purpose of enabling those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

[0046] (Implementation Method 1)

[0047] First, refer to Figure 1 A DCDC converter device 100 according to one embodiment of the present disclosure is described. Figure 1 As shown, the DCDC converter device 100 includes a CPU 101 , a battery 102 , a DCDC converter (boost / step-down) circuit 103 , and a capacitor 104 .

[0048] The DCDC converter device 100 serves as a vehicle-mounted power supply system. For example, when a voltage drop of the battery 102 occurs, power is supplied to a load (connected equipment, not shown) from a capacitor 104 serving as a power storage device used as an auxiliary power supply through voltage regulation of a DCDC converter (buck-boost) circuit 103.

[0049] CPU 101 monitors the voltage and current value of battery 102 and the voltage and current value of capacitor 104 , and controls DCDC converter circuit 103 so that the capacitor 104 is charged from battery 102 and discharged from capacitor 104 to battery 102 or load at a predetermined voltage and current.

[0050] The battery 102 is a vehicle-mounted battery and is connected to a motor, an engine starter, and the like.

[0051] The DCDC converter circuit 103 performs step-up and step-down of the DC voltage in a switching manner. The DCDC converter circuit 103 turns on / off the semiconductor switches S1-S4 respectively based on the PWM wave control signal from the CPU 101, and performs voltage conversion through the LC circuit. In addition, the DCDC converter circuit 103 detects the battery voltage / current value at the connection part between the battery 102 and the battery 102, outputs the battery voltage / current value to the CPU 101, and detects the battery voltage / current value at the connection part between the capacitor 104 and the capacitor voltage / current value to the CPU 101.

[0052] Auxiliary devices and ECUs (Engine Control Units) that operate with a smaller current than devices connected to battery 102 are connected to capacitor 104. Capacitor 104 and battery 102 charge and discharge each other to provide backup against voltage fluctuations of battery 102.

[0053] As a storage element for storing power, for example, a large-capacity electric double layer capacitor capable of rapid charge and discharge is used in capacitor 104. Capacitor 104 may be a capacitor other than an electric double layer capacitor or a storage element other than a capacitor such as a flywheel.

[0054] like Figure 2 As shown, the CPU 101 includes a step-up / down control unit 202, a PWM setting unit 203, a random number generating unit 204, a variation generating unit 205, an adding unit 206, a counter unit 207, and a comparing unit 208. The operation clock (CLK) is supplied to the CPU 101 by the oscillation circuit 201. The PWM generating unit 209 may be composed of the PWM setting unit 203, the random number generating unit 204, the variation generating unit 205, the adding unit 206, the counter unit 207, and the comparing unit 208.

[0055] Alternatively, the threshold value generating unit that generates the initial threshold value of the comparing unit 208 may be formed by the PWM setting unit 203 .

[0056] In addition, the step-up / down control unit 202, the PWM setting unit 203, the random number generation unit 204, the variation generation unit 205, the addition unit 206, the counter unit 207 and the comparison unit 208 are composed of hardware or software. For example, the counter unit 207 can be set as a timer circuit, and the comparison unit 208 can be set as a comparator, and each can be implemented by hardware.

[0057] The buck-boost control unit 202 calculates the buck-boost control value of the DCDC converter circuit 103 based on the counter reset timing from the counter unit 207 and the input from other control units (for example, start, ignition on, etc. timing) not shown, as well as the battery voltage / current value and the capacitor voltage / current value input from the outside, and outputs the command value given to each switch S1-S4 of the DCDC converter circuit 103 to the PWM setting unit 203. As an example, the calculation is an operation performed using real numbers using floating points.

[0058] The PWM setting unit 203 converts the command value set by the buck-boost control unit 202 into an on-count value (initial threshold value) corresponding to the on-time period of the PWM wave corresponding to the period T based on the counter reset timing from the counter unit 207. As an example, the on-count value is an integer. The on-count value is output to the adder 206. In addition, the PWM setting unit 203 sets the initial value for generating a random number to the random number generator 204, and outputs an update timing for each control cycle, which is a control cycle consisting of more than two cycles. In addition, the PWM setting unit 203 sets the control cycle (prescribed interval) and the code sequence of the variation to the variation generator 205.

[0059] After the initial value is set, the random number generator 204 generates a random number sequence according to the update timing from the PWM setting unit 203 , and outputs the generated random number sequence to the variation generator 205 .

[0060] The variation generation unit 205 generates a variation sequence obtained by multiplying the random number sequence from the random number generation unit 204 by a predetermined code sequence, and outputs the variation sequence to the addition unit 206. At this time, the variation generation unit 205 determines the code sequence so that the duty ratio is maintained in a predetermined interval (control period) consisting of two or more periods T.

[0061] The code sequence is a sequence in which the selected basic code sequence is repeated. The basic code sequence can be set to a sequence having a length corresponding to the control period and a total of 0. When the length is an even number, the basic code sequence can be a sequence in which the same number of +1 and -1 is set, that is, when the length is 2, it is set to {+1, -1}, and when the length is 4, it is set to {+1, +1, -1, -1}.

[0062] When the length is an odd number, coefficients such as {+1, +1, -2} may be used to make the basic code sequence a sequence whose total is 0. Also, when the length is an even number, coefficients such as {+1, +1, +1, -3} may be used.

[0063] The adding unit 206 adds each variation of the variation sequence to the on count value output from the PWM setting unit 203 at each cycle T, and generates a fluctuating on count value that fluctuates at each cycle T. The fluctuating on count value is output to the comparing unit 208 as a threshold value.

[0064] Here, when the addition of the variation to the on count value exceeds the range of the count value of the period T (is larger than the maximum count value or smaller than the minimum count value), the adder 206 does not add the variation to the on count value, but directly outputs the on count value. Alternatively, when the addition of the variation to the on count value exceeds the range of the count value of the period T (is larger than the maximum count value or smaller than the minimum count value), the variation generator 205 sets the variation to 0. Alternatively, the random value or code sequence may be set to 0.

[0065] The counter section 207 repeatedly increments the count value in each clock cycle and resets the count value when the count value reaches the maximum value, that is, when one cycle T is completed. The count value is output to the comparison section 208 .

[0066] Alternatively, the counter unit 207 may repeatedly perform the following actions, i.e., decrement the count value according to the clock cycle, and reset to the maximum count value when the count value reaches the minimum value, i.e., when one cycle T is completed. The counter unit 207 outputs the counter reset timing to the buck-boost control unit 202 and the PWM setting unit 203 at the timing of the reset, so that an interrupt is generated and the counter interrupt routine is started.

[0067] The comparison unit 208 compares the count value of the counter unit 207 with the variable conduction count value generated by the addition unit 206, and generates a PWM wave in such a manner that the H level (conduction) is output if the count value is smaller than the variable conduction count value, and the L level (off) is output if the count value is greater than or equal to the variable conduction count value. Alternatively, the comparison unit 208 may generate a PWM wave in such a manner that the H level (conduction) is output if the count value is greater than or equal to the variable conduction count value, and the L level (off) is output if the count value is smaller than the variable conduction count value.

[0068] Thus, the PWM wave generated according to the command value given to each switch of the DCDC converter circuit 103 is input to the DCDC converter circuit 103. The PWM wave input to the DCDC converter circuit 103 controls the switches S1-S4, thereby controlling the charging and discharging between the battery 102 and the capacitor 104 and the voltage step-up and step-down.

[0069] First, as a basic action, use Figure 3The following describes a case where the PWM generator 209 generates a PWM wave without performing SS on the command value from the step-up / step-down control unit 202. This is equivalent to turning off the operation of the random number generator 204, making the variation generated by the variation generator 205 zero, so that the PWM generator 209 outputs a PWM wave with the on count value input from the PWM setting unit 203 as a threshold.

[0070] The command value is a real value of, for example, 0.0 to 1.0, and is a value that instructs the ratio (duty ratio) of a predetermined switch-on time period within a command control cycle (for example, 2T). For example, the command value is latched (held) at each counter reset timing.

[0071] The counter section 207 increments and outputs the count value in each clock cycle. The counter section 207 generates a sawtooth wave by repeatedly performing the following operation in a cycle T (i.e., a cycle of counting a predetermined number of times). The operation is an operation of resetting the count value to the minimum count value when the count value exceeds the maximum count value.

[0072] Alternatively, the counter unit 207 may generate a sawtooth wave by repeatedly decreasing the count value from the maximum count value and resetting the count value to the maximum count value when the count value decreases to less than the minimum count value.

[0073] For example, if a 100 MHz clock is used, the minimum count value is set to 0, and the maximum count value is set to 999, the period T is a constant period of 10 usec (100 kHz). Counting is repeated 1000 times (counting times) from the minimum count value 0 to the maximum count value 999.

[0074] The PWM setting unit 203 converts the command value into an on count value corresponding to the number of counts of the cycle T (dashed line).

[0075] For example, when the command value is 0.5, the on-count value is 1000×0.5=500, which is obtained by multiplying the count number 1000 by the value. If 500 counts out of 1000 counts (for example, the period from the minimum count value 0 to the maximum count value 999 until the count reaches 500) are used as the on-time period, a pulse waveform with a duty cycle of 0.5 can be obtained.

[0076] The comparison unit 208 sets the output to H (ON) at the counter reset timing, and sets the output to L (OFF) at the timing when the count value exceeds the ON count value, thereby generating a PWM wave.

[0077] When using a sawtooth wave generated by decrementing the count value, the comparator 208 may set the output to H (on) at the counter reset timing and set the output to L (off) when the count value decreases to less than the on count value, thereby generating a PWM wave.

[0078] By repeating this operation, a PWM wave is generated at a constant cycle T.

[0079] use Figure 4A , Figure 4B The generation of PWM signals for buck-boost control is described below. Figure 4A , Figure 4B In the above example, S represents a step. Figure 4A An example of the main routine of the buck-boost control is shown below. Figure 4B An example of a counter interrupt routine that interrupts each time the counter is reset is shown. The main routine and the counter interrupt routine may also be composed of programs executed by a processor.

[0080] exist Figure 4A In S401 , for example, the buck-boost control unit 202 or the PWM setting unit 203 sets the period T or a maximum count value equivalent to the period T for the counter unit 207 .

[0081] In S402 , for example, the PWM setting unit 203 sets an initial value for generating a random number to the random number generating unit 204 .

[0082] In S403 , for example, the PWM setting unit 203 sets a control period (predetermined interval) and a code sequence of the variation in the variation generating unit 205 .

[0083] After these initial settings are performed in S401 to S403 , for example, the step-up / step-down control unit 202 operates the counter unit 207 in S404 to enable the counter interruption in order to start the counter interruption routine.

[0084] In S405 , for example, the buck-boost control unit 202 calculates a switching duty ratio of the buck-boost control based on the battery voltage / current detection value and the capacitor voltage / current detection value, and calculates a command value.

[0085] In S406 , for example, the step-up / step-down control unit 202 checks whether an operation end instruction has been received from another control unit.

[0086] When the step-up / step-down control unit 202 receives the operation end instruction (S406: Yes), the flow ends.

[0087] On the other hand, when the step-up / down pressure control unit 202 has not received the operation end instruction (S406: No), the flow returns to S405, and the step-up / down pressure control is performed again.

[0088] When a counter interrupt is generated according to the counter reset timing from the counter unit 207 during the execution of S405, the counter interrupt routine is started. Figure 4B S411 starts to execute.

[0089] exist Figure 4B In S411, for example, the PWM setting unit 203 latches (holds) the current command value (switching duty ratio).

[0090] In S412 , for example, the PWM setting unit 203 converts the command value into an on count value (initial threshold value) corresponding to the cycle T (number of counts) and equivalent to the on period of the PWM wave.

[0091] In S413 , for example, the random number generation unit 204 generates a random value to update the random number sequence.

[0092] In S414, for example, the variation generating unit 205 multiplies the updated random number sequence by the code sequence, and determines whether the value added to the conduction count value is less than the minimum count value or greater than the maximum count value. When the added value is less than the minimum count value or greater than the maximum count value, the variation generating unit 205 sets the variation to zero. When the added value is between the minimum count value and the maximum count value, the variation generating unit 205 multiplies the generated random number by the current code of the code sequence to set the variation, and outputs it to the adding unit 206. The adding unit 206 adds the set variation to the conduction count value to generate a variable conduction count value.

[0093] In addition, the adding unit 206 may add the variation to the count value instead of adding the variation to the on count value. The adding unit 206 receives the count value output from the counter unit 207 and the variation output from the variation generating unit 205, and may input the output of the adding unit 206 and the on count value output from the PWM setting unit 203 to the comparing unit 208. The counter unit 207 may count 1000 times from 50 to 1049, for example, or count 1000 times from -30 to 969, instead of counting from 0 to 999.

[0094] In S415, for example, the adding unit 206 outputs (sets) the variable conduction count value generated in S414 to the comparing unit 208, and the comparing unit 208 compares the variable conduction count value generated by the adding unit 206 with the count value input from the counter unit 207 to generate a PWM wave. If the PWM generating unit 209 generates a PWM wave (the PWM waveform becomes an L level), the counter interrupt routine is returned. Alternatively, when the counter unit 207 and the comparing unit 208 are executed in parallel by hardware or the like, the counter interrupt routine is returned at the time when the variable conduction count value is set.

[0095] use Figure 5 The generation of a spread spectrum PWM signal will be described.

[0096] PWM wave generation and Figure 3 The basic operation described in is the same as that described in , but in order to change the on-time period of the PWM wave, a random number sequence and a code sequence are used to change one of the inputs of the comparison unit 208 from the on-count value (dashed line) to the variable on-count value (single-dot chain line).

[0097] Here, an example is described in which the command value instructed by the buck-boost control unit 202 is updated once every two cycles. In this example, the control cycle is 2T, and the on-time period of the PWM wave is changed using a basic code sequence {+1, -1} of length 2.

[0098] The command value is a value of the duty ratio expressed by a real value between 0.0 and 1.0, and indicates the ratio of the time period in the cycle T during which a predetermined switch of the DCDC converter circuit 103 is turned on.

[0099] The random number sequence is updated according to the length of the basic code sequence corresponding to the control period. When a basic code sequence {+1, -1} of length 2 is used, the random number sequence is basically updated once every 2 periods. k ={r1, r1, r2, r2,…}.

[0100] The code sequence is a sequence in which the selected basic code sequence is repeated. When a basic code sequence {+1, -1} of length 2 is selected, the code sequence is {+1, -1, +1, -1, ...}.

[0101] The variation sequence is generated by multiplying each element of the random number sequence by each element of the code sequence. k = each element of {r1, r1, r2, r2, ...} is multiplied by the code sequence s k ={+1, -1, +1, -1, ...} to generate the variation sequence v k ={+r1,-r1,+r2,-r2,...}.

[0102] Figure 5 The example of a random number sequence in units of a control period (2T) is shown, but the present disclosure is not limited thereto, and the random number sequence may also be in units of periods other than the control period (2T). For example, the random number sequence may be in units of integer multiples of the control period (n×2T). In addition, the update timing of the command value may be different from the start timing of the random number sequence. In addition, the timing of the command value update may be different from the timing of the PWM wave generation (the rising timing of the PWM wave). For example, in the case where the command value is updated between T0-T1, T1 may be used as the start timing of the conduction count value. Moreover, the variation may be in units of real numbers instead of count values ​​(integers). In the case where the variation is a real number, the decimals below the decimal point may be considered in other periods, and the average value of multiple variations may be used as the variation. In the case where the variation is +50.5, -50.5, it may be set to +50, -50, +51, -51, so that the average value is +50.5, -50.5.

[0103] In addition, when the on-count value exceeds the range of the count value of the period T when the variation is added, the variation is set to 0. For example, when the variation (e.g., r3) is added to the on-count value at time T4 and exceeds the maximum count value, or when the variation (e.g., -r3) is added to the on-count value at time T5 (minus r3) and is less than the reset value (minimum count value), the control period of the code sequence is maintained and the random value r3 is set to 0 (making the variations v5 and v6 0). In this case, the variation sequence v k Become v k ={+r1,-r1,+r2,-r2,0,0,+r4,-r4,…}.

[0104] Alternatively, in the above case, the random value r3 may be set to 0 in any one of the cycles. In this case, the variation v5 may be set to 0, the random number sequence and the code sequence may be updated in v6, and the variation sequence v k Set to v k ={+r1,-r1,+r2,-r2,0,+r4,-r4,…}.

[0105] The counter section 207 increments the count value in accordance with the clock cycle from the oscillation circuit 201. The counter section 207 outputs a sawtooth wave by repeating an operation of resetting the count value when the count value reaches a maximum value corresponding to the cycle T.

[0106] For example, when a 100 MHz clock is used, if the minimum count value is 0 and the maximum count value is 1000 (the count value is 0 to 999), the count is set to 1000 times (counting number), and the cycle T is 10 usec (100 kHz).

[0107] The PWM setting unit 203 converts the command value into an on count value corresponding to the number of counts of the cycle T (dashed line).

[0108] The variable conduction count value (single-point dash line) is the conduction count value (dashed line) plus the variable sequence v k By setting the variable on count value as the threshold value in the comparison unit 208, the PWM generation unit 209 can generate a PWM wave in which the on time period is randomly varied while the duty ratio indicated by the command value is maintained at each control cycle.

[0109] For example, when the command value is 0.5, the count number 1000 is multiplied by this value, and the result is 1000×0.5=500, which is the conduction count value. k ={+10, -10, +25, -25, ...}, the obtained variable on count value is {510, 490, 525, 475, ...}. The PWM generation unit 209 uses the variable on count value to output a pulse waveform in which every 2 cycles are one control cycle and the duty ratio is 0.5 per control cycle. In the case where the on count value is not an integer, it is also possible to control in such a way that the average value of multiple cycles becomes the on count value. For example, in the case where the on count value based on the command value is 500.5, it is possible to use the on count value 501 after using the on count value 500 so that the average value of the on count value is 500.5. In this way, the duty ratio can be controlled more finely.

[0110] The comparison unit 208 generates a PWM wave by making the output H (on) when the count value is less than the threshold value (variable on count value), and making the output L (off) when the count value exceeds the threshold value. Alternatively, the comparison unit 208 generates a PWM wave by making the output L (off) when the count value is less than the threshold value (variable on count value), and making the output H (on) when the count value exceeds the threshold value.

[0111] An example of the operation at each time point will be described below.

[0112] Time point T0:

[0113] The command value is latched and d1 is held.

[0114] d1 is multiplied by the number of counts to convert into an on count value D1.

[0115] The random number sequence is updated, and the random value r1 taken from the random number sequence {r1, r1, r2, r2, ...} is maintained.

[0116] If D1+r1 exceeds the maximum count value, or D1-r1 is less than the minimum count value, then set v1=0. Otherwise,

[0117] Extract +1 from the code sequence {+1, -1, +1, -1, ...}, multiply it by the random value r1, and obtain the variation v1 = +r1.

[0118] It is assumed that the variation conduction count value vD1=D1+v1=D1+r1 is set as the threshold value of the comparison unit.

[0119] When the count value exceeds vD1, a PWM wave that becomes L (off) is generated, and the on-time period becomes an on-time period that is extended by r1 from the original on-time period.

[0120] Time point T1:

[0121] The held command value d1 (on count value D1) and random value r1 are used.

[0122] If D1+r1 exceeds the maximum count value, or D1-r1 is less than the minimum count value, then set v2=0. Otherwise,

[0123] Extract -1 from the code sequence {+1, -1, +1, -1, ...}, multiply it by the random value r1, and obtain the variation v2 = -r1.

[0124] It is assumed that the variation conduction count value vD2=D1+v2=D1-r1 is set as the threshold value of the comparison unit.

[0125] When the count value exceeds vD2, a PWM wave that becomes L (off) is generated, and thus the on-time period becomes an on-time period that is shortened by r1 from the original on-time period.

[0126] Time point T2:

[0127] The command value is latched and d2 is held.

[0128] d2 is multiplied by the number of counts to convert into an on count value D2.

[0129] The random number sequence is updated, and the random value r2 taken from the random number sequence {r1, r1, r2, r2, ...} is maintained.

[0130] If D2+r2 exceeds the maximum count value, or D2-r2 is less than the minimum count value, then set v3=0. Otherwise,

[0131] Extract +1 from the code sequence {+1, -1, +1, -1, ...}, multiply it by the random value r2, and obtain the variation v3 = +r2.

[0132] It is assumed that the variation conduction count value vD3=D2+v3=D2+r2 is set as the threshold value of the comparison unit.

[0133] When the count value exceeds vD3, a PWM wave that becomes L (off) is generated, and thus the on-time period becomes an on-time period that is extended by r2 from the original on-time period.

[0134] Time point T3:

[0135] The held command value d2 (on count value D2) and random value r2 are used.

[0136] If D2+r2 exceeds the maximum count value, or D2-r2 is less than the minimum count value, then set v4=0. Otherwise,

[0137] Extract -1 from the code sequence {+1, -1, +1, -1, ...}, multiply it by the random value r2, and obtain the variation v4 = -r2.

[0138] It is assumed that the variation conduction count value vD4=D2+v4=D2-r2 is set as the threshold value of the comparison unit.

[0139] When the count value exceeds vD4, a PWM wave that becomes L (off) is generated, and thus the on-time period becomes an on-time period that is shortened by an amount r2 from the original on-time period.

[0140] Time point T4:

[0141] The command value is latched and d3 is held.

[0142] d3 is multiplied by the maximum count value to be converted into the on count value D3.

[0143] The random number sequence is updated and the random value r3 is maintained.

[0144] In this example, since D3+r3 exceeds the maximum count value, the variation v5 is set to 0.

[0145] It is assumed that the variation conduction count value vD5=D3+v5=D3, and this is set as the threshold value of the comparison unit.

[0146] When the count value exceeds vD5, a PWM wave that becomes L (off) is generated, and thus the on-time period becomes the same as the original on-time period.

[0147] Here, it is assumed that the variation v3 is set to 0 for one cycle (T4 to T5), so the command value is latched and the random number sequence is updated at T5, similarly to the time points T0 and T2.

[0148] While maintaining the control cycle length of the code sequence so that v5=v6=0 for two cycles, the same operation as that at time point T4 is performed at time point T5.

[0149] By repeating these operations, the on-time period of each PWM wave can be varied by maintaining the duty ratio in each control period (2T) at a constant period T without varying the period T of the generated PWM wave.

[0150] use Figure 6A to Figure 6D Here, an example of a PWM wave with a duty ratio of 50% (the ratio of the on-time period to the off-time period is the same) is shown.

[0151] Fig. 6A , Figure 6C Indicates the situation without SS. Figure 6B , Fig.6D It shows the situation of SS in which the present disclosure is performed. Fig. 6A , Figure 6B The time waveform of the PWM wave (the horizontal axis is time, the vertical axis is the amplitude level) is shown. Figure 6C , Fig.6D Indicates the frequency spectrum of the PWM wave (the horizontal axis is frequency, the vertical axis is power spectrum density [dB / Hz]).

[0152] From the timeline point of view, Fig. 6A compared to, Figure 6B In the case of a PWM wave with a longer on-time period and a PWM wave with a shorter on-time period, the PWM wave is repeated every 2 cycles. Fig. 6A The conduction time period (t12) in the even-numbered cycle PWM wave has a longer conduction time period than Fig. 6A The conduction period (t34) in the circuit is a short conduction period, and the amplitude of the variation changes every 2 cycles.

[0153] exist Figure 6C In the PWM wave without SS, the level of the higher harmonics of the PWM wave is high, but Fig.6D As shown, by performing the SS of the present disclosure, the energy of the frequencies of the line spectrum is dispersed (the gaps are filled), and the level of the higher harmonics is reduced.

[0154] use Figure 7 The random number generation unit will be described.

[0155] After the initial value is set, the random number generator 204 generates a random number sequence according to the update timing from the PWM setting unit 203 , and outputs the random value to the variation generator 205 .

[0156] Figure 7 In FIG. 1 , as an example, a random number generator using a logistic map is shown. The logistic map is a map that can generate a complex sequence with a simple structure. In addition, a random number sequence can also be generated using a method other than the logistic map.

[0157] Logistic map with x n+1 =ax n (1.0-x n ) is expressed by a difference equation, given the parameter a and the initial value x 0 , to generate a non-periodic sequence x called chaos whose complexity varies based on parameter a n .

[0158] When a=4.0 and 0 <X 0 <1, the logistic map can produce x n = a complex random sequence in the range of [0.0, 1.0].

[0159] Set the initial value of the random number generator to 0.0 <x 0 <1.0, and parameter a (=4.0), and updating register X at each update timing, thereby generating a random sequence.

[0160] The output value is normalized so as to be within a predetermined range and used as the variation.

[0161] In addition, when a = 4.0, due to the generated x n The frequency of occurrence of values ​​near 0 and 1 in the range of [0.0, 1.0] is high, so the random number may be generated in the following manner: n Within the specified range (for example, 0.1 <x n <0.9), adopt this value, and in other cases update again to find a new x n .

[0162] use Figure 8 Here, an example of generating a new fluctuation amount sequence by overlapping code sequences having different control period lengths is shown.

[0163] In code sequence 1, {+1, -1} is repeated so that the duty ratio is maintained at a control period of 2T.

[0164] The code sequence 1 is multiplied by the random number sequence 1, i.e., {r1_1, r1_1, r1_2, r1_2, r1_3, r1_3}, to generate the variation sequence 1, i.e., {+r1_1, -r1_1, +r1_2, -r1_2, +r1_3, -r1_3}.

[0165] On the other hand, in code sequence 2, {+1, +1, +1, -1, -1, -1} is repeated so that the duty ratio is maintained at a control period of 6T.

[0166] The code sequence 2 is multiplied by the random number sequence 2, i.e., {r2_1, r2_1, r2_1, r2_1, r2_1, r2_1}, to generate the variation sequence 2, i.e., {+r2_1, +r2_1, +r2_1, -r2_1, -r2_1}.

[0167] The superimposed variation sequence {+r1_1+r2_1, -r1_1+r2_1, +r1_2+r2_1, -r1_2-r2_1, +r1_3-r2_1, -r1_3-r2_1} is generated by superimposing (adding) the variation sequence 1 and the variation sequence 2. By using the superimposed variation sequence, a variation with further increased randomness can be added to the PWM wave.

[0168] Figure 8 The first six cycles of an example in which random number sequence 1 is {2, 2, 3, 3, 5, 5}, basic code sequence 1 is {+1, -1}, random number sequence 2 is {4, 4, 4, 4, 4}, and basic code sequence 2 is {+1, +1, +1, -1, -1, -1} are shown. Random number sequence 1 is multiplied by code sequence 1 to generate variable sequence 1, namely {+2, -2, +3, -3, +5, -5}, and random number sequence 2 is multiplied by code sequence 2 to generate variable sequence 2, namely {+4, +4, +4, -4, -4, -4}. Variation sequence 1 and variation sequence 2 are added to generate an overlapping variation sequence {+6, +2, +7, -7, +1, -9}.

[0169] In this example, the start (phase) of the control period of the two variation sequences coincides, but the start of the two variation sequences may be staggered. For example, variation sequence 1 may start at T0, while variation sequence 2 may start at T1. In addition, three or more variation sequences may be overlapped.

[0170] When the command value changes gradually and the period of time in a stable state is long, the duty ratio of the PWM wave can be roughly maintained even if a code sequence with a long control cycle length is used.

[0171] (Effects of Embodiment 1)

[0172] According to the first embodiment, by resetting the counter unit at a certain period, it is possible to perform software control in which the processing time does not change. In addition, by generating a PWM wave based on the variation, a PWM wave with a spread spectrum can be generated. Furthermore, by generating the variation in such a way that the total of the variation in each control period consisting of more than two certain periods is 0, it is possible to improve the spread spectrum effect while making it easier to maintain the duty cycle in each control time period. In addition, when the value obtained by adding the variation to the threshold exceeds the maximum count value of the counter unit or is less than the minimum count value of the counter unit, the variation is set to 0, thereby making the duty cycle in each control time period reliably maintained. In addition, by generating random numbers based on the logistic map, random numbers can be simply generated. In addition, by overlapping more than two variation sequences having different control periods, a PWM wave in which the energy of the frequency of the line spectrum is more appropriately dispersed can be generated.

[0173] (Implementation Method 2)

[0174] exist Fig. 9 The second embodiment is different from the first embodiment in that the buck-boost control unit 202 inputs the buck-boost control mode to the PWM setting unit 203 .

[0175] When the change time period of the command value (whether it is a gentle change or a sudden change) changes according to the step-up / step-down control mode, the PWM setting unit 203 may change the control cycle length (predetermined interval length) to a corresponding length.

[0176] For example, when high-speed control is performed in a short period of time, a short control period (e.g., 2T) is used. On the other hand, when a slow control is performed in a long period of time, such as in a stable state with less changes, a long control period (e.g., 6T) can also be used, and a multi-period overlapping sequence can be used to further improve the randomness of the spread spectrum.

[0177] To this end, the buck-boost control unit 202 inputs information related to the current buck-boost control mode to the PWM setting unit 203. The PWM setting unit 203 can change the control cycle and the cycle of the random number generation (update) timing (the frequency of generating random numbers) according to the control mode input from the buck-boost control unit 202.

[0178] (Effects of Embodiment 2)

[0179] According to the second embodiment, a PWM wave having a spectrum spread corresponding to the step-up and step-down control mode can be generated.

[0180] In the above-mentioned embodiments, the expression "...part" used in each structural element may be replaced by other expressions such as "...circuitry", "...component", "...device", "...unit" or "...module".

[0181] Although the embodiments are described above with reference to the accompanying drawings, the present disclosure is not limited to these examples. It is obvious that a person skilled in the art can think of various variations or modifications within the scope of the claims. It should be understood that these variations or modifications also belong to the technical scope of the present disclosure. In addition, the various structural elements in the embodiments can be arbitrarily combined within the scope of the present disclosure.

[0182] The present disclosure can be implemented by software, hardware or software in collaboration with hardware. Each functional block used in the description of the above-mentioned embodiments may also be partially or entirely implemented as an LSI (Large Scale Integration) as an integrated circuit, and each process described in the above-mentioned embodiments may also be partially or entirely controlled by an LSI or a combination of LSIs. The LSI may be composed of individual chips, or may be composed of one chip in a manner that includes part or all of the functional blocks. The LSI may also include input and output of data. Depending on the degree of integration, the LSI is sometimes also referred to as "IC (Integrated Circuit)", "system LSI", "super LSI" or "extra large LSI".

[0183] The method of integrated circuitization is not limited to LSI, and can also be implemented by a dedicated circuit, a general-purpose processor or a dedicated processor. In addition, an FPGA (Field Programmable Gate Array) that can be programmed after LSI manufacturing, or a reconfigurable processor (Reconfigurable Processor) that can reconfigure the connection or setting of the circuit block inside the LSI can also be used. The present disclosure can also be implemented as digital processing or analog processing.

[0184] Furthermore, if integrated circuit technology that replaces LSI emerges as semiconductor technology advances or other technologies are derived, it is of course possible to use this technology to achieve integration of functional blocks. There is also the possibility of applying biotechnology, etc.

[0185] The disclosed contents of the specification, drawings, and abstract contained in the Japanese patent application No. 2022-119572 filed on July 27, 2022 are incorporated herein by reference in their entirety.

[0186] Industrial Applicability

[0187] One embodiment of the present disclosure is useful for a switching power supply system.

[0188] Description of Reference Numerals

[0189] 101CPU

[0190] 102 Batteries

[0191] 103DCDC converter (boost and buck) circuit

[0192] 104 Capacitor

[0193] 201 Oscillator Circuit

[0194] 202 Buck-Boost Control Unit

[0195] 203 PWM setting unit

[0196] 204 Random number generation unit

[0197] 205 Variation Generation Unit

[0198] 206 Addition Department

[0199] 207 Counter unit

[0200] 208 Comparison Department

Claims

1. A PWM wave generating device, characterized in that: include: A counter circuit that generates a count value that is reset at a certain period; A threshold generation circuit that generates an initial threshold; a variation generating circuit for generating the variation so that the total of the variation in each control period consisting of two or more of the certain periods becomes 0; and The comparison circuit compares a value based on the count value with a threshold value based on the initial threshold value, and generates a PWM wave, ie, a pulse width modulation wave, based on the variation amount.

2. The PWM wave generating device according to claim 1, wherein: the value based on the count value is the count value, The threshold value based on the initial threshold value is a value obtained by adding the initial threshold value to the variation amount.

3. The PWM wave generating device according to claim 1, wherein: The value based on the count value is a value obtained by adding the count value to the variation. The threshold value based on the initial threshold value is the initial threshold value.

4. The PWM wave generating device according to claim 1, wherein: It also has a random number generating circuit for generating a random number in each control cycle, The variation generation circuit generates a variation sequence using the random number and a basic code sequence whose sum is 0 in each control cycle. When a value obtained by adding the threshold value to the fluctuation amount of the fluctuation amount series exceeds the maximum count value of the counter unit or is smaller than the minimum count value of the counter unit, the fluctuation amount is set to zero.

5. The PWM wave generating device according to claim 4, wherein: The random number generation circuit uses a logistic map, that is, x n+1 =ax n (1.0-x n ) to generate random numbers.

6. The PWM wave generating device according to claim 4, wherein: The variation is generated by overlapping two or more variation sequences having different control cycles.

7. A DCDC converter control device, characterized in that: The invention comprises the PWM wave generating device according to claim 1, and controls a DCDC converter circuit, i.e., a DC-DC converter circuit, based on the PWM wave.

8. A DCDC converter control device, characterized in that: The invention comprises the PWM wave generating device according to claim 4, and controls a DCDC converter circuit based on the PWM wave, wherein the variation sequence is changed in accordance with a change in a step-up / step-down control mode in the PWM wave generating device.

9. A DCDC converter, characterized in that: include: The DCDC converter control device according to claim 7 or 8; and The DCDC converter circuit.

10. A PWM wave generation method, characterized in that: The following steps are involved: Generate a count value that is reset at a certain period; Generate initial thresholds; generating the variation amount so that the total of the variation amounts in each control period consisting of two or more of the certain periods becomes 0; and A value based on the count value is compared with a threshold value based on the initial threshold value, and a PWM wave is generated based on the variation amount.

11. A DCDC converter control method, characterized in that: The DCDC converter is controlled based on the PWM wave obtained by the PWM wave generation method according to claim 10.

12. A program, characterized in that The processor is caused to execute the PWM wave generating method as claimed in claim 10.

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