JP6428351B2 - Power control device - Google Patents

Description

  The present invention relates to a power supply control device that supplies power to a load.

  Electromagnetic noise (hereinafter referred to as “switching noise”) generated from a switching power supply and having a switching frequency or its multiplied frequency may affect the operation of peripheral devices.

  For example, when the frequency selected in the radio is close to the frequency of the switching noise, noise due to the switching noise may be superimposed on the sound output from the radio, which may cause discomfort to the user. In addition to radio, if switching noise of a specific frequency occurs, it may be affected by the switching noise.

  Various techniques for reducing the influence of switching noise generated from a switching power supply on the surroundings have been proposed. Patent Document 1 describes a technique for randomly changing a switching frequency. Patent Document 2 describes a technique for dispersing switching noise energy by changing a switching frequency when an operating state of a load is stable. Patent Document 3 describes a technique for continuously sweeping a switching frequency within a predetermined range.

JP 2003-153526 A Japanese Patent No. 4461842 Japanese Patent No. 4628434

  However, in the technique described in Patent Document 1, when the switching frequency that is randomly changed substantially matches a specific frequency (for example, a radio tuning frequency) that may affect the operation of the peripheral device, Peripheral devices may be affected by switching noise, such as noise.

  Also in the technique described in Patent Document 2, depending on the switching frequency that is changed when the load operation is stable, there is a possibility that the operation of the peripheral device may be affected by substantially matching the specific frequency of the peripheral device. Also in the technique described in Patent Literature 3, the switching frequency to be swept may substantially match the specific frequency of the peripheral device, which may affect the operation of the peripheral device.

  The present invention has been made in view of the above problems, and an object thereof is to suppress the influence on the operation of peripheral devices due to switching noise generated from a switching power supply.

The power supply control device of the present invention made to solve the above problems includes a switching power supply, a determination unit, and a load control unit.
The switching power supply is configured to output DC power having a predetermined voltage value and change the output power by changing the switching frequency.

  The determination unit acquires information related to the switching frequency and performs determination based on the acquired information. Specifically, at least one of electromagnetic noise having the same frequency as the switching frequency generated from the switching power supply and electromagnetic noise of each n-order frequency n times (n is a natural number of 2 or more) of the switching frequency is targeted. Determine whether any one of the at least one target electromagnetic noise as electromagnetic noise may affect the operation at the specific frequency for a specific device having the specific frequency as an operation parameter To do.

  The load control unit supplies power from the switching power supply when it is determined by the determination unit that any of the at least one target electromagnetic noise may affect the operation of the specific device at a specific frequency. The power consumption of at least one specific load among the at least one load that operates in response to the operation is increased or decreased.

  In the power supply control device configured as described above, when it is determined that any one of the target electromagnetic noises may affect the operation at a specific frequency in the specific device, the load control unit performs at least one specific Increase or decrease the power consumption of the load. That the power consumption of the specific load is increased or decreased means that the power output from the switching power supply is increased or decreased. Here, the switching power supply of the present embodiment is configured to change the output power by changing the switching frequency.

  Therefore, when the power consumption of the specific load is increased or decreased, the switching frequency of the switching power supply fluctuates (increases or decreases) as a result. Thereby, it becomes possible to suppress that the target electromagnetic noise affects the operation of the specific device.

  In addition, the code | symbol in the parenthesis described in the claim shows the correspondence with the specific means as described in embodiment mentioned later as one aspect, Comprising: The technical scope of this invention is limited is not.

It is a block diagram which shows the power supply control system of 1st Embodiment. It is explanatory drawing for demonstrating that a switching frequency is fluctuate | varied by a load fluctuation function. It is a circuit diagram which shows the specific structural example of a dummy load part. It is a flowchart which shows the load fluctuation control process of 1st Embodiment. It is a block diagram which shows the power supply control system of 2nd Embodiment. It is a flowchart which shows the load fluctuation control process of 2nd Embodiment. It is a block diagram which shows the power supply control system of 3rd Embodiment. It is a flowchart which shows the load fluctuation control process of 3rd Embodiment.

Embodiments to which the present invention is applied will be described below with reference to the drawings.
[First Embodiment]
(1) Configuration of Power Supply Control System A power supply control system according to the first embodiment shown in FIG. 1 is mounted on a vehicle and configured to control supply of power supply power to a plurality of loads in the vehicle. As shown in FIG. 1, the power control system of the first embodiment includes a battery 1, a power control IC 10, a power supply unit 16, a microcomputer 20, a load circuit 30, a display 101, a touch panel 102, and a radio. And a tuner 103.

  The battery 1 is configured to be able to output a battery voltage VB having a predetermined voltage value (for example, 12 V). The battery 1 is charged with a battery charging voltage from a power source for battery charging, such as a battery charging voltage based on power generated by a vehicle generator (not shown) or a battery charging voltage based on power supplied from outside the vehicle. Is done.

  The battery voltage VB of the battery 1 is input to at least the power supply control IC 10 and the power supply unit 16. Note that the battery voltage VB is not always supplied directly from the battery 1 to the power supply control IC 10 and the power supply unit 16. When the charging power source is capable of supplying the battery charging voltage and the voltage value is higher than the battery voltage VB of the battery 1, the power control IC 10 and the power supply unit 16 are directly connected A battery charging voltage is supplied from a charging power source.

  The power supply control IC 10 has a function of generating a DC voltage having a predetermined voltage value (that is, generating DC power) based on the input voltage (battery voltage VB or battery charging voltage) and outputting it as the power supply voltage Vc. The power supply voltage Vc from the power supply control IC 10 is supplied to at least the load circuit 30.

  The power supply control IC 10 includes a switching regulator 11. In FIG. 1, the switching regulator is represented as “Sw.Reg.”. In the power supply control IC 10, a power supply voltage generation unit including at least the switching regulator 11 generates a power supply voltage Vc from the battery voltage VB and outputs it.

  Various configurations of the power supply voltage generation unit are conceivable. For example, a configuration in which another power supply circuit is provided before the switching regulator 11 may be employed. Further, for example, a configuration in which another power supply circuit is provided after the switching regulator 11 may be employed. Further, for example, a configuration in which another power supply circuit is connected in parallel to the switching regulator 11 may be employed. As another power supply circuit, for example, a series regulator, a series connection configuration of a DC / AC converter and an AC / DC converter, or the like can be considered. Of course, a configuration in which the battery voltage VB is substantially stepped down to the power supply voltage Vc by only the switching regulator 11 may be output.

  The switching regulator 11 is a pulse frequency modulation (PFM) type switching regulator. The switching frequency fs of the switching regulator 11 varies according to the output power (in other words, according to the output current) in order to generate the power supply voltage Vc having a constant voltage value regardless of the variation of the output power to be supplied to the load. To do.

  Specifically, the switching frequency fs increases as the output power increases within a frequency band predetermined in the specification, and conversely decreases as the output power decreases. The fluctuation amount of the output power and the fluctuation amount of the switching frequency fs are in a substantially proportional relationship.

  In the first embodiment, as an example, it is assumed that the switching frequency fs during the operation of the switching regulator 11 fluctuates within a 1 MHz band, that is, within a predetermined frequency band that is substantially centered at 1 MHz.

  As illustrated in FIG. 2A, the switching frequency fs of the first embodiment that transitions in the 1 MHz band has the highest probability of 1 MHz, and the occurrence probability of the switching frequency fs has a normal distribution centered on 1 MHz. Close probability distribution. In addition, 1 MHz with the highest occurrence probability is hereinafter referred to as a specified center frequency fs0.

  The occurrence probability distribution shown in FIG. 2A is a schematic probability distribution for simply explaining that the switching frequency fs varies depending on the load. How the switching frequency fs actually varies depends on the type and number of loads, the operating state, and the like.

  The power supply unit 16 steps down the battery voltage VB to generate and output a power supply voltage Vd having a predetermined voltage value. The power supply voltage Vd from the power supply unit 16 is supplied to at least the microcomputer 20. That is, the microcomputer 20 operates upon receiving the supply voltage Vd from the power supply unit 16.

  The display 101 is a display device that can display an image. The display 101 is controlled by the microcomputer 20 via the display control unit 32 in the load circuit 30.

  The touch panel 102 is an input device for accepting an input operation by direct contact by a user. The touch panel 102 is arranged so as to overlap the display 101. The user's operation content on the touch panel 102 is transmitted to the microcomputer 20 via the operation input processing unit 33 in the load circuit 30.

  The radio tuner 103 receives a radio broadcast signal, selects (tunes), demodulates it, extracts an audio signal, and outputs the audio signal to an audio output unit (not shown), thereby outputting the audio signal of the radio broadcast being received as an audio signal. Output from the unit.

  The load circuit 30 includes a dummy load unit 34 in addition to various loads such as a DRAM 31, a display control unit 32, and an operation input processing unit 33. The dummy load unit 34 operates together with the DRAM 31, the display control unit 32, the operation input processing unit 33, and the like as a load of the power supply control IC 10, that is, a load operated by the power supply voltage Vc supplied from the power supply control IC 10. The load of the power supply control IC 10 includes a load operated via the load circuit 30 such as the display 101 and the touch panel 102 in addition to the load circuit 30.

  The microcomputer 20 is a known computer including a CPU, a ROM, a RAM, an I / O, and the like, and implements various functions by executing various processes according to programs stored in the ROM or other storage devices. Functions realized by the microcomputer 20 include a navigation function and an audio function. The microcomputer 20 controls operations of various control objects such as the load circuit 30 and the radio tuner 103 in order to realize these various functions.

  For example, the microcomputer 20 causes the display 101 to display various information related to the navigation function and the audio function, various operation menus, various selection menus, and the like. Various selection menus include radio tuning frequencies.

  For example, the microcomputer 20 outputs a sound signal corresponding to the function being executed from a sound output unit (not shown). For example, when the execution of the radio function is selected by the user, the audio signal of the selected radio broadcast is output from the audio output unit. Thereby, the user can listen to the radio broadcast program of each radio station. In addition, when execution of the TV function is selected by the user, the broadcast signal of the selected TV channel is received and demodulated, the audio signal is output from the audio output unit, and the video is displayed on the display 101. Display.

  For example, the microcomputer 20 acquires the content of the operation performed on the touch panel 102 by the user through the operation input processing unit 33 of the load circuit 30 and executes various processes according to the operation content. For example, when a list of radio stations stored in advance is displayed on the display 101 and a user selects a specific radio station via the touch panel 102, the frequency of the radio station is selected. The radio tuner 103 is controlled to select a radio wave. The user can select an arbitrary frequency via the touch panel 102.

  When receiving the designation of the tuning frequency fr from the microcomputer 20, the radio tuner 103 extracts a radio wave of the designated tuning frequency fr by the tuning circuit, generates an audio signal from the radio wave by the demodulation circuit, and outputs the audio signal. Output to the section.

  Furthermore, the microcomputer 20 of the first embodiment has a load variation function. The load variation function is a function of controlling the operation of the dummy load unit 34 by outputting a load control signal Sc to the dummy load unit 34 of the load circuit 30. Specifically, the power consumption by the dummy load unit 34 It is a function to control. The specific configuration of the dummy load unit 34 and the specific contents of the load variation function will be described in detail later.

  The microcomputer 20 can acquire information related to the switching frequency fs of the switching regulator 11. Specifically, in the first embodiment, data indicating a specified noise band and an n-fold specified noise band, which will be described later, is stored in a ROM in the microcomputer 20 or another storage device. The microcomputer 20 can recognize the specified noise band and the n-fold specified noise band by reading the stored data. However, the method for obtaining the specified noise band and the n-fold specified noise band in this way is merely an example.

(2) Description of the load variation function The load variation function by the microcomputer 20 will be specifically described. The microcomputer 20 can control the power consumption in the dummy load unit 34 by the load variation function. When the power consumption in the dummy load unit 34 changes, the power supplied from the power supply control IC 10 changes. As described above, the control of the output power in the power supply control IC 10 is performed by changing the switching frequency fs of the switching regulator 11. Therefore, the switching frequency fs can be changed by changing the power consumption in the dummy load unit 34.

  Here, the relationship between the switching frequency fs of the switching regulator 11 and the frequency selected by the radio tuner 103 (channel selection frequency fr) will be described. The switching regulator 11 generates a set switching frequency fs itself and electromagnetic noise (switching noise) having a frequency that is n times the switching frequency fs.

  In the following description, a frequency n times the actual switching frequency fs is also referred to as an n-multiplied frequency fsn. Specifically, the n-multiplied frequency fsn of the first embodiment is up to a double-multiplied frequency fs2, a triple-multiplied frequency fs3,..., An N-multiplied frequency fsN. Further, a frequency n times the specified center frequency fs0 is also referred to as an n-fold specified center frequency fs0n. Specifically, the n-fold prescribed center frequency fs0n is up to a two-fold prescribed center frequency fs02, a three-fold prescribed center frequency fs03,..., an N-times prescribed center frequency fs0N.

  The predetermined band including the specified center frequency fs0 is also referred to as a specified noise band. The specified noise band is a band in which there is a possibility that noise is superimposed on radio sound when the channel selection frequency fr is set within this band. A predetermined band including the n-multiplied prescribed center frequency fs0n for each n-multiplied prescribed center frequency fs0n is also referred to as an n-multiplied prescribed noise band. Specifically, the n-fold prescribed noise band is defined as a two-fold prescribed noise band including the two-fold prescribed center frequency fs02, a three-fold prescribed noise band including the three-fold prescribed center frequency fs03,. Up to N times the specified noise band. Each of these n-multiplied prescribed noise bands is a band where there is a possibility that noise will be superimposed on the radio sound when the channel selection frequency fr is set within that band.

  A predetermined band including the actual switching frequency fs is also referred to as an actual noise band. This actual noise band is a band where there is a possibility that noise will be superimposed on radio sound when the channel selection frequency fr is set within this band. A predetermined band including the n-multiplied frequency fsn for each n-multiplied frequency fsn is also referred to as an n-multiplied actual noise band. Specifically, the n-fold actual noise band is a 2-fold real noise band including the 2-fold frequency fs2, a 3-fold real noise band including the 3-fold frequency fs3,..., an N-fold real noise including the N-fold frequency fsN. There is even a bandwidth. Each of these n-multiplied real noise bands is a band in which there is a possibility that noise will be superimposed on radio sound when the channel selection frequency fr is set within that band.

  When the channel selection frequency fr of the radio tuner 103 is included in any one of the specified noise band and the n-fold specified noise band of the switching regulator 11, noise is superimposed on the audio signal output from the radio tuner 103, and the noise is The sound may be output from a sound output unit such as a speaker or a headphone, which may cause discomfort to the user.

  Further, the channel selection frequency fr of the radio tuner 103 is included in an actual noise band including the actual switching frequency fs of the switching regulator 11 or an n multiplied actual noise band including the n multiplied frequency fsn for each n multiplied frequency. In some cases, noise may be superimposed on the audio signal output from the radio tuner 103.

  In particular, when the channel selection frequency fr of the radio tuner 103 matches one of the actual switching frequency fs and the n-multiplied frequency fsn of the switching regulator 11, there is a possibility that noise is superimposed on the audio signal output from the radio tuner 103. Increase more.

  In other words, if any one of the specified center frequency fs0 and the n-multiplied specified center frequency fs0n of the switching regulator 11 is included in the selected frequency band including the selected frequency fr of the radio tuner 103, the radio tuner 103 outputs it. It can be said that there is a possibility that noise is superimposed on the audio signal.

  Further, if any one of the actual switching frequency fs and the n-multiplied frequency fsn of the switching regulator 11 is included in the channel selection frequency band including the channel selection frequency fr of the radio tuner 103, the audio signal output from the radio tuner 103 is included. It can be said that noise may be superimposed.

  Therefore, in the first embodiment, when the microcomputer 20 executes the load variation function, when the possibility that noise caused by switching noise is superimposed on radio sound becomes a certain level or more, the possibility is reduced. In order to do so, the dummy load unit 34 is controlled.

  Specifically, the microcomputer 20 normally performs control so that the power consumption in the dummy load unit 34 becomes zero. When the channel selection frequency fr of the radio tuner 103 is included in any one of the specified noise band and the n-fold specified noise band of the switching regulator 11, there is a possibility that noise caused by the switching noise is superimposed on the radio sound. Is determined to be equal to or greater than a certain level, the dummy load unit 34 is operated, and power is consumed in the dummy load unit 34. When the dummy load unit 34 is activated, the switching regulator 11 increases the switching frequency fs to supplement the power supplied to the dummy load unit 34.

  As described above, the switching frequency fs of the switching regulator 11 according to the first embodiment fluctuates according to the load (that is, according to the supplied power) around the specified center frequency fs0 of 1 MHz. An example of the probability of occurrence of the switching frequency fs in this case is as shown in FIG. 2 (a), where the specified center frequency fs0 of 1 MHz has the highest occurrence rate, and a probability distribution close to the normal distribution as a whole. Yes.

  In this case, if the channel selection frequency fr by the radio tuner 103 is set to a specified noise band (for example, 900 kHz to 1.1 MHz) including the specified center frequency fs0 as illustrated in FIG. There is a possibility that noise due to switching noise may be superimposed on the audio signal from.

  Therefore, when the channel selection frequency fr is set within the specified noise band, the dummy load unit 34 is operated to shift the switching frequency fs to a higher value by a certain amount. For example, by operating the dummy load unit 34, the value is shifted to a value higher by 0.2 MHz as illustrated in FIG. The fact that the switching frequency fs is shifted to a value higher by 0.2 MHz due to an increase in the load means that the specified center frequency fs0 is also shifted from 1 MHz to 1.2 MHz, and accordingly, the specified noise band is also shifted upward by 2 MHz as a whole. And a predetermined band including 1.2 MHz.

  As a result, the frequency band affected by the switching noise can be excluded from the channel selection frequency fr of the radio tuner 103, and the noise due to the switching noise can be prevented from being superimposed on the audio signal from the radio tuner 103.

  When the specified center frequency fs0 is shifted to 1.2 MHz, the n-fold specified center frequency is also shifted upward. That is, the frequency is n MHz multiplied by 1.2 MHz. Along with this, the n-fold specified noise band is also shifted upward.

  There are various methods for determining whether or not there is a possibility that noise due to switching noise is superimposed on a sound signal output from the radio tuner 103 (hereinafter also referred to as “noise superimposition determination method”). Four noise superimposition determination methods A to D are shown below.

  Determination method A: The above-described determination method. That is, a method of determining whether or not the channel selection frequency fr of the radio tuner 103 is included in either the specified noise band of the switching regulator 11 or the n-fold specified noise band that is a harmonic band thereof. When the channel selection frequency fr is included in either the specified noise band or the n-fold specified noise band of the switching regulator 11, it can be determined that there is a possibility of being affected by switching noise (noise superimposition).

  Determination method B: A method for determining whether or not the channel selection frequency fr of the radio tuner 103 is included in either the actual noise band of the switching regulator 11 or an n-multiplied actual noise band that is a harmonic band thereof. When the channel selection frequency fr is included in either the actual noise band or the n-fold actual noise band of the switching regulator 11, it can be determined that there is a possibility of being affected by switching noise (noise superimposition).

  Determination method C: Whether or not any of the actual switching frequency fs of the switching regulator 11 and the n-multiplied frequency fsn that is a harmonic thereof is included in the tuning frequency band including the tuning frequency fr of the radio tuner 103. How to determine whether. When any one of the switching frequency fs and the n-multiplied frequency fsn is included in the selected frequency band, it can be determined that there is a possibility of being affected by switching noise (noise superimposition). Note that it may be determined whether any one of the switching frequency fs and the n-multiplied frequency fsn matches the tuning frequency fr.

  Determination method D: Whether any of the specified center frequency fs0 of the switching regulator 11 and the n-multiplied specified center frequency fs0n that is a harmonic thereof is included in the selected frequency band including the selected frequency fr of the radio tuner 103. A method of determining whether or not. When either one of the specified center frequency fs0 and the n-fold specified center frequency fs0n is included in the selected frequency band, it can be determined that there is a possibility that the influence (switching noise) of the switching noise is more than a certain level.

  The microcomputer 20 of the first embodiment implements a load variation function using the determination method A among the four noise superimposition determination methods of the determination methods A to D. In the second embodiment and the third embodiment to be described later, the determination method B and the determination method C will be specifically described.

(3) Configuration Example of Dummy Load A specific configuration of the dummy load unit 34 will be described with reference to FIG. As shown in FIG. 3A, the dummy load section 34 of the first embodiment has one dummy load cell 36 in which a resistor R1 and a switch 37 are connected in series. One end of the resistor R1 is connected to one end of the switch 37. The other end of the switch 37 is connected to a ground line (ground potential). The power supply voltage Vc from the power supply control IC 10 is applied to the other end of the resistor R1.

  The switch 37 is turned on / off by a load control signal Sc from the microcomputer 20. Various specific configurations of the switch 37 are conceivable. For example, a semiconductor switching element may be used.

  The microcomputer 20 normally turns off the switch 37 so that the power consumption in the dummy load unit 34 becomes zero. If there is a possibility that noise due to switching noise may be superimposed on the radio sound, that is, if the channel selection frequency fr is included in either the specified noise band or the n-multiplied specified noise band of the switching regulator 11, a dummy is used. The load part 34 is operated. That is, by turning on the switch 37, power is consumed in the dummy load unit 34.

  Various other configurations of the dummy load are conceivable, for example, a dummy load unit 41 illustrated in FIG. 3B and a dummy load unit 61 illustrated in FIG. These dummy load portions 41 and 61 will be described in a third embodiment to be described later.

(4) Description of Load Fluctuation Control Process The load fluctuation control process executed by the microcomputer 20 for realizing the load fluctuation function will be described with reference to FIG. When the execution of the radio function is selected by the user and the radio tuner 103 starts the radio broadcast reception process, the CPU of the microcomputer 20 reads the load fluctuation control process program of FIG. 4 from the ROM or another storage device. Execute periodically and repeatedly. The aforementioned determination method A is used in the load fluctuation control process of FIG.

  When the load variation control process of FIG. 4 is started, the CPU of the microcomputer 20 acquires the channel selection frequency fr currently selected in the radio tuner 103 in S110. In the first embodiment, as described above, the microcomputer 20 transmits the channel selection frequency fr selected by the user to the radio tuner 103 so that the radio tuner 103 selects the channel selection frequency fr. It is configured. Therefore, the microcomputer 20 always grasps the channel selection frequency fr set in the radio tuner 103. If the microcomputer 20 is not configured to directly control the radio tuner 103, information on the channel selection frequency fr may be acquired by inquiring the channel selection frequency fr to the radio tuner 103.

  In S120, it is determined whether or not the channel selection frequency fr is included in the specified noise band or the n-fold specified noise band (n = 2 to N) of the switching regulator 11. If the tuning frequency fr is not included in either the specified noise band or the n-fold specified noise band (S120: NO), the process proceeds to S180.

  In S180, it is determined whether or not the radio reception has been completed, that is, whether or not the reception process by the radio tuner 103 has been completed by the user performing an operation to end the execution of the radio function. If radio reception has not ended (S180: NO), the process returns to S110. When the radio reception is completed (S180: YES), the operation of the dummy load unit 34 is stopped in S190. At this time, when the dummy load portion 34 is not operating, the state is maintained. In S200, the specified noise band and the n-fold specified noise band are returned to their initial states. In the first embodiment, the initial state is each specified noise band when the specified center frequency fs0 is 1 MHz.

  If the channel selection frequency fr is included in the specified noise band or the n-fold specified noise band in S120 (S120: YES), the process proceeds to S130. In S130, it is determined whether or not the dummy load unit 34 is already operating, that is, whether or not the switch 37 is already turned on.

  When the dummy load unit 34 is not operated (that is, when the switch 37 is turned off) (S130: NO), the dummy load unit 34 is operated in S140. That is, the switch 37 is turned on. In S150, the specified noise band and the n-fold specified noise band are shifted upward from the initial state. In the first embodiment, since the specified center frequency fs0 is shifted from 1 MHz to 1.2 MHz by the operation of the dummy load unit 34, the process of S150 is based on the specified center frequency fs0 (1.2 MHz) after the shift. This process shifts each specified noise band. That is, the specified noise band is shifted to a predetermined band including 1.2 MHz. Each of the n-multiplied specified noise bands is also shifted to a predetermined band including the n-multiplied frequency of 1.2 MHz. After the process of S150, the process proceeds to S180.

  If the dummy load unit 34 is already operating (S130: YES), the operation of the dummy load unit 34 is stopped in S160. That is, the switch 37 is turned off. In S170, the specified noise band and the n-fold specified noise band are returned to their initial states. That is, when the operation of the dummy load unit 34 is stopped, the specified center frequency fs0 returns from 1.2 MHz to 1 MHz. Therefore, the processing of S170 is performed based on the specified center frequency fs0 (1 MHz) after the return. This process returns the noise band to the initial state. After the processing of S170, the process proceeds to S180.

  In the first embodiment, data indicating the specified noise band and the n-fold specified noise band in the initial state (when the dummy load unit 34 is not operating) is stored in the ROM in the microcomputer 20 or other storage device. Has been. However, each of these data may be configured to be acquired from the power supply control IC 10 as necessary. Alternatively, the specified center frequency fs0 is configured to be acquired, the n-fold specified center frequency fs0n is calculated from the acquired specified center frequency fs0, and based on the specified center frequency fs0 and the n-fold specified center frequency fs0n, The specified noise band and the n-fold specified noise band in the initial state may be derived by calculation. There are various possible methods for the microcomputer 20 to acquire the specified noise band and the n-fold specified noise band.

(5) Effects of the First Embodiment As described above, in the power supply control system of the first embodiment, the microcomputer 20 generates noise caused by switching noise in the radio sound based on the channel selection frequency fr of the radio tuner 103. It is determined whether or not there is a possibility of overlapping. Specifically, it is determined whether or not the channel selection frequency fr is included in either the specified noise band or the n-fold specified noise band of the switching regulator 11 (S120). If it is included, the output power from the power supply control IC 10 is increased (that is, the output power from the switching regulator 11 is increased) by operating the dummy load section 34.

  Since the switching regulator 11 of the first embodiment is a PFM switching regulator, the increase in output power is realized by increasing the switching frequency fs. That is, when the dummy load unit 34 is operated, the switching regulator 11 increases the switching frequency fs in order to increase the output power in order to supply power to the dummy load unit 34.

  As a result, the specified noise band and the n-fold specified noise band are shifted upward according to the increase of the switching frequency fs, whereby the channel selection frequency fr can be excluded from the specified noise band and the n-fold specified noise band. it can.

  The dummy load unit 34 is different from other various loads such as the display control unit 32 and the operation input processing unit 33 in order to intentionally increase / decrease the output power from the power supply control IC 10, that is, a load variation function. It is provided for realization. By providing the dummy load portion 34 in this manner, the output power from the power supply control IC 10 can be arbitrarily increased or decreased without affecting various functions of the vehicle and without considering the effects on the various functions. it can.

  Further, the dummy load unit 34 has a simple configuration including a resistor R1 and a switch 37 (that is, including one dummy load cell 36). And the increase / decrease in the power consumption by the dummy load part 34 is performed by ON / OFF of the switch 37. FIG. Therefore, the output power of the power supply control IC 10 can be increased or decreased with a simple configuration and method while suppressing an increase in cost and an increase in size of the apparatus.

[Second Embodiment]
The power supply control system of the second embodiment shown in FIG. 5 has the same configuration as that of the power supply control system of the first embodiment shown in FIG. Therefore, the same components as those in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and description thereof is omitted.

There are at least three main differences between the power supply control system of the second embodiment and the power supply control system of the first embodiment.
The first difference is that the power supply unit 16 is not provided in the second embodiment, and the microcomputer 22 is operated by the power supply voltage Vc from the power supply control IC 10. That is, the microcomputer 20 is a load of the power supply control IC 10.

  The second difference is the noise superimposition determination method. In the first embodiment, the noise superimposition determination is performed using the determination method A among the determination methods A to D. However, in the second embodiment, the noise superimposition determination is performed using the determination method B. That is, it is determined whether or not the channel selection frequency fr of the radio tuner 103 is included in either the actual noise band of the switching regulator 11 or the n-times multiplied actual noise band that is a harmonic band thereof.

  In order to use this determination method B, the microcomputer 22 needs to know the actual switching frequency fs of the switching regulator 11. There are various methods for determining the actual switching frequency fs. For example, a method of acquiring information on the switching frequency fs from the power supply control IC 10 by data communication or the like can be considered. Further, for example, a method of obtaining based on the power supply voltage Vc or the output current output from the power supply control IC 10 can be considered.

  In the second embodiment, the microcomputer 22 acquires the switching frequency fs based on the output current output from the power supply control IC 10. Specifically, a current sensor 8 for detecting a current flowing through the energization path (that is, an output current from the power supply control IC 10) is provided on the energization path from the power supply control IC 10 to the load. The microcomputer 22 can know the actual switching frequency fs in real time by acquiring and processing the current detection signal from the current sensor 8.

  The third difference is a method of shifting the switching frequency fs, that is, a method of increasing or decreasing the output power from the power supply control IC 10. In the first embodiment, the method of operating or stopping the dummy load unit 34 is used. In the second embodiment, in addition to the method of operating or stopping the dummy load unit 34, the power consumption of the microcomputer 22 itself is increased or decreased. Also controls.

  In the second embodiment, the microcomputer 22 itself is a load of the power supply control IC 10. For this reason, when the power consumption of the microcomputer 22 varies, the switching frequency fs of the switching regulator 11 also varies accordingly. Therefore, the microcomputer 22 also has a function of shifting the switching frequency fs by intentionally increasing or decreasing its power consumption.

  Specifically, the increase / decrease of the power consumption by the microcomputer 22 is performed depending on whether or not a dummy calculation prepared in advance is executed. A program for dummy calculation is stored in advance in the ROM of the microcomputer 22 or other storage device. Specific contents of the dummy calculation can be determined as appropriate. For example, it may be content that repeatedly executes simple addition and subtraction, or content that executes division that cannot be divided. The microcomputer 22 performs a dummy calculation when it is desired to increase the load and shift the switching frequency fs to the high band side. Conversely, when it is desired to reduce the load and shift the frequency fs to the lower band side, the dummy calculation is stopped.

  The load variation control process of the second embodiment will be described with reference to FIG. When the CPU of the microcomputer 22 starts the load variation control process of FIG. 6, the channel selection frequency fr currently selected in the radio tuner 103 is acquired in S210. In S220, the switching frequency fs is acquired. That is, the current actual switching frequency fs is acquired based on the current detection signal from the current sensor 8.

  The microcomputer 22 derives an actual noise band that is a predetermined band including the switching frequency fs based on the actual switching frequency fs acquired in S220. Furthermore, the microcomputer 22 derives an n-multiplied frequency fsn, which is a frequency of each harmonic component of the n-multiplied (multiplied by 2 to N) based on the acquired switching frequency fs. Then, for each n-multiplied frequency fsn, an n-multiplied actual noise band that is a predetermined band including the n-multiplied frequency is derived.

  In S230, it is determined whether or not the channel selection frequency fr is included in the actual noise band or the n-fold actual noise band of the switching regulator 11. When the tuning frequency fr is not included in either the actual noise band or the n-fold actual noise band (S230: NO), the process proceeds to S300.

  In S300, it is determined whether or not the radio reception is completed. If radio reception has not ended (S300: NO), the process returns to S210. When radio reception is completed (S300: YES), the operation of the dummy load unit 34 is stopped in S310. Further, in S320, the dummy calculation by the microcomputer 20 itself (that is, the CPU itself) is stopped. If a dummy calculation has not been performed, that state is maintained.

  If the channel selection frequency fr is included in the actual noise band or the multiplied actual noise band in S230 (S230: YES), the process proceeds to S240. In S240, it is determined whether the CPU itself is already executing a dummy calculation. If the dummy calculation has not yet been executed (S240: NO), the dummy calculation is started in S250, and the process proceeds to S300.

  If the dummy calculation is already being executed (S240: YES), it is determined in S260 whether or not the dummy load unit 34 is already operating. If the dummy load unit 34 is not activated (S260: NO), the dummy load unit 34 is activated in S270, and the process proceeds to S300.

If the dummy load unit 34 is already operating (S260: YES), the operation of the dummy load unit 34 is stopped in S280, the dummy calculation is further stopped in S290, and the process proceeds to S300.
As described above, also in the power supply control system according to the second embodiment, there is a possibility that the microcomputer 22 may superimpose noise caused by switching noise on the radio sound based on the channel selection frequency fr of the radio tuner 103. Determine whether or not.

  Specifically, it is determined whether or not the channel selection frequency fr is included in either the actual noise band or the n-fold actual noise band (S230). If it is included, the output power from the power supply control IC 10 is increased (that is, the output power from the switching regulator 11 is increased) by operating the dummy load section 34.

  As a result, the actual noise band and the n-fold actual noise band are shifted upward according to the increase in the switching frequency fs, and the channel selection frequency fr can be excluded from the actual noise band and the n-fold actual noise band.

  Moreover, in the second embodiment, since the actual switching frequency fs of the switching regulator 11 is acquired and the determination is performed based on the actual switching frequency fs, the switching frequency fs and the n-multiplied frequency fsn are selected. It is possible to move away more reliably from the frequency fr, and the influence on radio sound due to switching noise can be suppressed more reliably.

[Third Embodiment]
The power supply control system of the third embodiment shown in FIG. 7 has the same configuration as the power supply control system of the first embodiment shown in FIG. Therefore, the same components as those in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and description thereof is omitted.

There are at least four main differences between the power supply control system of the third embodiment and the power supply control system of the first embodiment.
The first difference is the configuration of the power supply control IC 50. The power supply control IC 50 of the third embodiment includes a first power supply voltage generator and a second power supply voltage generator as power supply voltage generators for supplying power to the outside.

  The first power supply voltage generation unit includes at least a first switching regulator 51, and generates and outputs a first DC power supply voltage Vc1. The second power supply voltage generator includes at least a second switching regulator 52, and generates and outputs a DC second power supply voltage Vc2.

  The configuration of the first switching regulator 51 is exactly the same as that of the switching regulator 11 of the first embodiment. And the 1st power supply voltage Vc1 output from the 1st power supply voltage generation part containing the 1st switching regulator 51 is the same value (for example, 5V) as the power supply voltage Vc of 1st Embodiment.

  The second switching regulator 52 has basically the same configuration as the first switching regulator 51, but the value of the generated power supply voltage is different. That is, the second power supply voltage generation unit including the second switching regulator 52 generates and outputs a second power supply voltage Vc2 (for example, 3.3 V) having a value different from the first power supply voltage Vc1. Therefore, the voltage generated by the second switching regulator 52 is lower than the voltage generated by the first switching regulator 51.

  The first switching regulator 51 is configured so that the switching frequency fs1 changes in the 1 MHz band, while the second switching regulator 52 is configured such that the switching frequency fs2 changes in the 330 kHz band, for example. ing. That is, the switching frequency fs2 of the second switching regulator 52 varies within a predetermined frequency band with 330 kHz as the specified center frequency fs0 and approximately the specified center frequency fs0 as the center.

  In the following description, the first power supply voltage generation unit including the first switching regulator 51 is also referred to as “1 MHz system power supply”, and the second power supply voltage generation unit including the second switching regulator 52 is referred to as “330 kHz system power supply”. Also called.

  The power supply control IC 50 outputs switching information indicating the switching frequencies fs1 and fs2 of the switching regulators 51 and 52 to the microcomputer 24 by data communication.

  The second difference from the first embodiment is a noise superimposition determination method. In the third embodiment, noise superimposition determination is performed on each of the 1 MHz power supply and the 330 kHz power supply using the determination method C among the determination methods A to D described above.

  That is, for a 1 MHz system power supply, any one of the actual switching frequency fs1 of the first switching regulator 51 and the n-multiplied frequency fs1n that is a harmonic thereof includes the tuning frequency fr of the radio tuner 103. It is determined whether or not it is included in the frequency band. If included, the switching frequency fs1 should be increased or decreased based on the difference between the included frequency and the tuning frequency fr (hereinafter also referred to as “first difference”). The first increase / decrease width df1 is calculated. And according to the 1st increase / decrease width df1, the 1st dummy load part 41 in the load circuit 40 is controlled.

  The first increase / decrease width df1 is a value such that the influence of switching noise does not affect radio sound. Specifically, it is a value that can be shifted from the selected frequency band by shifting the frequency included in the selected frequency band among the switching frequency fs1 and the n-multiplied frequency fs1n. For this reason, the smaller the first difference is, the larger the first increase / decrease width df1 is to shift the switching frequency fs1 more. Conversely, the larger the first difference is, the smaller the amount by which the switching frequency fs1 should be shifted is.

  Whether the switching frequency fs1 is shifted in the upward direction or the downward direction can be appropriately determined. For example, when the switching frequency fs1 is included in the channel selection frequency band, when the switching frequency fs1 is higher than the channel selection frequency fr, the switching frequency fs1 is shifted upward, and the switching frequency fs1 is lower than the channel selection frequency fr. May shift the switching frequency fs1 in the decreasing direction.

  When either one of the switching frequency fs1 and the n-multiplied frequency fs1n is included in the channel selection frequency band, the switching frequency fs1 is set as long as the included frequency can be shifted and removed from the channel selection frequency band. It can be determined appropriately as to whether to shift in the upward direction or downward direction, and to what extent.

  The noise superimposition determination for the 330 kHz power supply is basically the same as that for the 1 MHz power supply. That is, even for a 330 kHz power source, any one of the actual switching frequency fs2 of the second switching regulator 52 and the n-multiplied frequency fs2n that is a harmonic thereof includes the tuning frequency fr of the radio tuner 103. It is determined whether it is included in the band.

  If included, the switching frequency fs2 should be increased or decreased based on the difference between the included frequency and the channel selection frequency fr (hereinafter also referred to as “second difference”). The second increase / decrease width df2 is calculated. Then, the second dummy load unit 61 in the load circuit 60 is controlled according to the second increase / decrease width df2.

  The second increase / decrease width df2 is a value that prevents the influence of switching noise on the radio sound. Specifically, the value included in the channel selection frequency band by shifting the frequency included in the channel selection frequency band out of the switching frequency fs2 of the second switching regulator 52 and the n-multiplication frequency fs1n multiplied by n. It is. For this reason, the smaller the second difference is, the larger the second increase / decrease width df2 is to shift the switching frequency fs2 more greatly. Conversely, the greater the second difference, the smaller the amount by which the switching frequency fs2 should be shifted, so the 21st increase / decrease width df2 becomes smaller.

  In order to use the determination method C, the microcomputer 24 needs to know the actual switching frequencies fs1 and fs2 of the switching regulators 51 and 52. In the third embodiment, the microcomputer 24 acquires the switching frequencies fs1 and fs2 based on the switching information output from the power supply control IC 50.

  In the microcomputer 24, there are a mixture of components that operate using the first power supply voltage Vc1 as a power source and components that operate as a second power source voltage Vc2. Therefore, the microcomputer 24 is supplied with both the first power supply voltage Vc1 and the second power supply voltage Vc2. That is, the microcomputer 24 itself is a load for both the 1 MHz power source and the 330 kHz power source.

  The third difference from the first embodiment is the configuration of the dummy load unit included in the load circuit 40. In the third embodiment, the load circuit 40 includes a first dummy load unit 41. The specific configuration of the first dummy load unit 41 is as shown in FIG. As shown in FIG. 3B, the first dummy load unit 41 has a variable resistor 42. One end of the variable resistor 42 is connected to the ground line, and the power supply voltage Vc (the first power supply voltage Vc1 from the 1 MHz power supply in this embodiment) is applied to the other end.

  The resistance value of the variable resistor 42 can be changed, for example, within a range from several tens of MΩ to several tens of Ω, which is close to the insulation level. When the resistance value of the variable resistor 42 changes, the resistance value of the first dummy load unit 41 as viewed from the 1 MHz power supply changes, and thereby the power consumption of the first dummy load unit 41 also changes. The resistance value of the variable resistor 42 is controlled by the first load control signal Sc1 from the microcomputer 24. The resistance value of the variable resistor 42 is hereinafter also referred to as “dummy resistance value Rs1”.

  In the initial state after startup, the microcomputer 24 sets the dummy resistance value Rs1 to a predetermined intermediate value. The specific value of the intermediate value can be determined as appropriate. For example, the value may be determined within a predetermined range including an intermediate value of the variable width.

  If there is a possibility that noise due to switching noise of the first switching regulator 51 may be superimposed on the radio sound, the power consumption in the first dummy load unit 41 is controlled by changing the dummy resistance value Rs1. Specifically, the switching frequency fs1 is changed from the current value to a resistance value that can be varied (increased or decreased) by the first increase / decrease width df1. Since the variable resistor 42 is used, the dummy resistance value Rs1 can be continuously changed, and thus the power consumption can be continuously changed. However, it is not essential to change continuously, and a configuration in which the dummy resistance value Rs1 is changed stepwise may be used.

  A fourth difference from the first embodiment is that a load circuit 60 that operates with a 330 kHz power supply is provided separately from the load circuit 40 that operates with a 1 MHz power supply. The load circuit 60 includes various circuits, modules, and the like that operate using the second power supply voltage Vc2 as a power source. One of them is a second dummy load section 61.

  A specific configuration of the second dummy load section 61 is as shown in FIG. As shown in FIG. 3C, the second dummy load unit 61 includes a plurality of dummy load cells 36 and a switch control unit 62. The dummy load cell 36 has the same configuration as the dummy load cell 36 of the first embodiment shown in FIG. 3A and includes a resistor R1 and a switch 37. The plurality of dummy load cells 36 are connected in parallel to each other, and the second power supply voltage Vc2 is applied to each dummy load cell 36.

  The switches 37 included in each dummy load cell 36 are individually controlled by the switch control unit 62. The switch control unit 62 individually controls each switch 37 of each dummy load cell 36 in accordance with the second load control signal Sc2 input from the microcomputer 24. The resistance value of the entire second dummy load unit 61, that is, the parallel combined resistance value of the plurality of dummy load cells 36 is also referred to as “dummy combined resistance value Rs2”.

  In the initial state after startup, the microcomputer 24 operates the specified number of the dummy load cells 36 of the second dummy load unit 61 to set the dummy combined resistance value Rs2 to a predetermined reference value. The prescribed number can be determined as appropriate. For example, about half of the total number of dummy load cells 36 may be activated.

  When there is a possibility that noise due to switching noise of the second switching regulator 52 may be superimposed on the radio sound, the microcomputer 24 changes the dummy combined resistance value Rs2 to reduce the power consumption in the second dummy load unit 61. Control. Specifically, the switching frequency fs2 is changed from the current value to a resistance value that can be varied (increased or decreased) by the second increase / decrease width df2.

  The load variation control process of the third embodiment will be described with reference to FIG. When the CPU of the microcomputer 24 starts the load fluctuation control process of FIG. 8, in S410, the first dummy load unit 41 is caused to set the dummy resistance value Rs1 to an intermediate value by the first load control signal Sc1. In S420, the dummy combined resistance value Rs2 is set to the reference value by operating the specified number of dummy load cells 36 by the second load control signal Sc2 with respect to the second dummy load unit 61.

  In S430, the channel selection frequency fr currently selected by the radio tuner 103 is acquired. In S440, the switching frequencies fs1 and fs2 of the switching regulators 51 and 52 are acquired based on the switching information input from the power supply control IC 50.

  The microcomputer 22 derives the frequency of each harmonic component based on the actual switching frequencies fs1 and fs2 acquired in S440. That is, for the switching frequency fs1 of the 1 MHz system power supply, the n-multiplied frequency fs1n that is the frequency of each harmonic component of the n-multiplied frequency (doubled to N-multiplied) is derived. Similarly, for the switching frequency fs2 of the 330 kHz system power supply, an n-multiplied frequency fs2n that is a frequency of each n-fold harmonic component is derived.

  In S450, noise superimposition determination for 1 MHz system power supply is performed. That is, any one of the switching frequency fs1 of the first switching regulator 51 and the n-multiplied frequency fs1n (hereinafter, collectively referred to as “first determination target frequency”) is selected by the radio tuner 103. It is determined whether it is included in the selected frequency band including the station frequency fr.

  If none of the first determination target frequencies is included in the selected frequency band (S450: NO), the process proceeds to S490. If any of the first determination target frequencies is included in the selected frequency band (S450: YES), the process proceeds to S460. In S460, based on the difference (first difference) between the first applicable frequency that is determined to be included in the channel selection frequency band among the first determination target frequencies and the channel selection frequency fr, the first A first increase / decrease width df1 that is a fluctuation width of the switching frequency fs1 necessary for removing the corresponding frequency from the channel selection frequency band is calculated.

  In S470, the dummy resistance value Rs1 corresponding to the first increase / decrease width df1 calculated in S460 is calculated. That is, a value that can change (increase or decrease) the switching frequency fs1 from the current value by the first increase / decrease width df1 is calculated as the dummy resistance value Rs1. In S480, the first dummy load unit 41 is caused to set the dummy resistance value Rs1 to the value obtained by the calculation of S470 by the first load control signal Sc1. After the processing of S480, the process proceeds to S490.

  In S490, noise superimposition determination for the 330 kHz power source is performed. That is, any one of the switching frequency fs2 of the second switching regulator 52 and the n-multiplied frequency fs2n (hereinafter, collectively referred to as “second determination target frequency”) is selected by the radio tuner 103. It is determined whether or not it is included in the selected frequency band including the station frequency fr.

  If none of the second determination target frequencies is included in the selected frequency band (S490: NO), the process proceeds to S530. If any one of the second determination target frequencies is included in the selected frequency band (S490: YES), the process proceeds to S500. In S500, based on the difference (second difference) between the second applicable frequency, which is a frequency determined to be included in the selected frequency band among the second determination target frequencies, and the second selected frequency fr, A second increase / decrease width df2 that is a fluctuation width of the switching frequency fs2 necessary for removing the corresponding frequency from the selected frequency band is calculated.

  In S510, the dummy combined resistance value Rs2 corresponding to the second increase / decrease width df2 calculated in S500 is calculated. That is, a value that can change (increase or decrease) the switching frequency fs2 from the current value by the second increase / decrease width df2 is calculated as the dummy combined resistance value Rs2. In S520, the second dummy load unit 61 is caused to set the dummy combined resistance value Rs2 to the value obtained by the calculation of S510 by the second load control signal Sc2. That is, the number of dummy load cells 36 corresponding to the value is operated so that the dummy combined resistance value Rs2 becomes the value obtained by the calculation of S510. After the processing of S520, the process proceeds to S530.

  In S530, it is determined whether or not the radio reception is completed. If radio reception has not ended (S530: NO), the process returns to S430. When the radio reception is completed (S530: YES), the dummy resistance value Rs1 of the first dummy load unit 41 is set to an initial value in S540. The initial value can be appropriately determined. For example, the initial value may be set to the maximum value of the entire variable width. By setting the maximum value, the power consumption in the first dummy load unit 41 when the radio function is not used can be suppressed to almost zero.

In S550, the operation of all the dummy load cells 36 in the second dummy load unit 61 is stopped. Thereby, the power consumption by the second dummy load unit 61 becomes zero.
As described above, also in the power supply control system of the third embodiment, there is a possibility that the microcomputer 24 may superimpose noise caused by the switching noise on the radio sound based on the channel selection frequency fr of the radio tuner 103. Determine whether or not. The determination is made individually for each of a plurality of power supply systems having different switching frequencies.

If there is a possibility that noise due to switching noise is superimposed on radio sound for each power supply system, the dummy load unit in the corresponding power supply system is controlled.
Therefore, it is possible to suppress the influence from any switching noise of each power supply system.

  In the third embodiment, the first dummy load portion 41 has a variable resistor 42 as shown in FIG. The microcomputer 24 controls the output power of the 1 MHz power supply by controlling the resistance value of the variable resistor 42 (that is, the dummy resistance value Rs1). Moreover, the microcomputer 24 appropriately controls the dummy resistance value Rs1 in accordance with the difference between the tuning frequency fr and the switching frequency fs and the difference between the tuning frequency fr and the n-multiplied frequency fsn. Therefore, the microcomputer 24 can change the switching frequency fs1 of the 1 MHz power supply by an appropriate amount in an appropriate direction.

  Further, as shown in FIG. 3C, the second dummy load unit 61 has a configuration in which a plurality of dummy load cells 36 are connected in parallel. Then, the microcomputer 24 targets the 330 kHz power source, and the number of dummy load cells 36 to be turned on according to the difference between the switching frequency fs2 and the channel selection frequency fr and the difference between the n-multiplied frequency fs2n and the channel selection frequency fr. To control. For this reason, the microcomputer 24 can change the switching frequency fs2 of the 330 kHz power supply by an appropriate amount in an appropriate direction.

[Other Embodiments]
As mentioned above, although embodiment of this invention was described, this invention can take a various form, without being limited to the said embodiment.

  (1) As a specific circuit configuration of the dummy load unit, the circuit configurations illustrated in FIGS. 3A to 3C are merely examples. As long as the resistance value can be switched between at least two types, dummy load portions having various configurations can be employed.

  (2) As one of the methods for dynamically changing the switching frequency of the switching regulator, in each of the above embodiments, the method of changing the resistance value by providing the dummy load portion has been described. However, the dummy load portion is provided. It is not essential.

  For example, by stopping the operation of any of the various components that make up the load circuit, conversely starting the stopped components, or changing the amount of operation of the components that are operating, the load It is also possible to vary the power consumption of the circuit and thereby vary the switching frequency.

  As long as the switching frequency of the switching regulator can be intentionally changed (that is, as long as the output power from the switching regulator can be intentionally changed), how to change the power consumption of which load is appropriately determined I can decide.

  (3) When the switching frequency can be sufficiently varied only by the dummy calculation of the microcomputer, the output power adjustment using the dummy load unit or another load may not be performed.

  (4) Various specific methods of changing the switching frequency by the dummy calculation of the microcomputer are conceivable in addition to the method shown in the second embodiment. For example, three types of dummy calculations with different processing loads (that is, different power consumption during execution) are prepared, and in the initial state, a dummy calculation with a medium processing load is executed, and the subsequent noise superimposition determination result The dummy calculation to be executed may be switched according to the above.

  (5) The determination method A is employed in the system configuration of the first embodiment, the determination method B is employed in the system configuration of the second embodiment, and the determination method C is employed in the system configuration of the third embodiment. However, these are only examples. For example, any of the determination methods B to D may be employed in the system configuration of the first embodiment.

When there are a plurality of power sources having different switching frequencies as in the third embodiment, different determination methods may be adopted for each system.
(6) Although the four types of determination methods A to D are shown as the noise superimposition determination method in the above embodiment, the determination may be performed using a method other than these. Further, a predetermined specified noise band including the specified center frequency fs0, a predetermined n multiplied specified noise band including the n multiplied specified center frequency fs0n, a predetermined actual noise band including the actual switching frequency fs, and a predetermined including the n multiplied frequency fsn. The predetermined channel frequency band including the n-fold actual noise band and the channel selection frequency fr can be determined as appropriate within a range in which the object of suppressing noise superimposition on radio sound can be achieved. In addition, the number of harmonic components to be considered can be determined as appropriate. For example, the fundamental wave to the 3rd harmonic may be considered, the fundamental wave to the 5th harmonic may be considered, or even higher harmonics may be considered.

  (7) In the above embodiment, the power supply control system configured to be able to suppress the influence of switching noise on the radio channel selection frequency has been described. It is not limited to frequency. The present invention can be applied to all types and forms of systems in which the effect of switching noise occurs when switching noise of a specific frequency occurs.

(8) The present invention is not limited to application to a power supply control system mounted on a vehicle. The present invention can also be applied to power supply control systems other than vehicles.
(9) In addition, the functions of one component in the above embodiment may be distributed as a plurality of components, or the functions of a plurality of components may be integrated into one component. Further, at least a part of the configuration of the above embodiment may be replaced with a known configuration having the same function. Moreover, you may abbreviate | omit a part of structure of the said embodiment. In addition, at least a part of the configuration of the above embodiment may be added to or replaced with the configuration of the other embodiment. In addition, all the aspects included in the technical idea specified only by the wording described in the claim are embodiment of this invention.

  DESCRIPTION OF SYMBOLS 1 ... Battery, 8 ... Current sensor 10, 50 ... Power supply control IC, 11 ... Switching regulator, 16 ... Power supply part, 20, 22, 24 ... Microcomputer, 30, 40, 60 ... Load circuit, 31 ... DRAM, 32 ... Display control unit 33 ... Operation input processing unit 34 ... Dummy load unit 36 ... Dummy load cell 37 ... Switch 41 ... First dummy load unit 42 ... Variable resistor 51 ... First switching regulator 52 ... First 2 switching regulators, 61, second dummy load section, 62, switch control section, 101, display, 102, touch panel, 103, radio tuner, R1, resistance.

Claims (8)

Switching power supplies (11, 51, 52) configured to output DC power of a predetermined voltage value and change the output power by changing the switching frequency;
The information about the switching frequency is acquired, and based on the acquired information, the electromagnetic noise having the same frequency as the switching frequency and the electromagnetic noise of each n-order frequency n times the switching frequency (n is a natural number of 2 or more) At least one target electromagnetic noise, and any one of the at least one target electromagnetic noise may affect the operation at the specific frequency for the specific device (103) having the specific frequency as an operation parameter. A determination unit (20, 22, 24) for determining whether or not there is
When the determination unit determines that any one of the at least one target electromagnetic noise may affect the operation of the specific device at the specific frequency, power is supplied from the switching power supply. The power consumption of the at least one specific load is increased or decreased by controlling the operation of at least one specific load (34, 41, 61) out of the at least one load that receives and operates. Load control units (20, 22, 24),
Equipped with a,
The load control unit includes a microcomputer (22) that performs a function as the load control unit,
The microcomputer functions as the specific load, and is configured to increase or decrease the power consumption of the microcomputer itself by executing a specific calculation by the microcomputer itself.
The power supply control apparatus characterized by the above-mentioned. The power supply control device according to claim 1,
The load control unit has a large difference between the frequency of the target electromagnetic noise determined by the determination unit as having a possibility of affecting the operation at the specific frequency in the specific device and the specific frequency. As described above, the power control device increases or decreases the power consumption of the at least one specific load. The power supply control device according to claim 1 or 2 ,
As the specific load, comprising a power consumption unit (34, 41, 61) configured to switch the power consumption continuously or stepwise in accordance with an input load control signal,
The power control device, wherein the load control unit is configured to increase or decrease power consumption in the power consumption unit by outputting the load control signal to the power consumption unit. The power supply control device according to claim 3 ,
The power consuming unit includes at least one resistive load (R1),
The power control device, wherein the load control unit is configured to increase or decrease power consumption in the power consumption unit by individually controlling energization to the at least one resistive load. The power supply control device according to claim 3 ,
The power consuming unit includes a variable resistance load (42) capable of controlling a resistance value,
The power control device, wherein the load control unit is configured to increase or decrease power consumption in the power consumption unit by controlling a resistance value of the variable resistance load. The power supply control device according to any one of claims 1 to 5 ,
The determination unit (22) uses at least one of the switching frequency and each of the n-th frequencies as a power supply frequency, and the specific frequency includes the power supply frequency for each of the at least one power supply frequency. The determination is performed by determining whether or not the power supply side frequency band is a predetermined frequency band, and the specific frequency is included in any of the power supply side frequency bands. In this case, it is determined that the target electromagnetic noise of the power supply side frequency included in the power supply side frequency band may affect the operation at the specific frequency in the specific device. . The power supply control device according to any one of claims 1 to 5 ,
The determination unit (24) uses at least one of the switching frequency and each n-th frequency as a power supply side frequency, and any one of the at least one power supply side frequency includes the specific frequency range. The power source included in the specific frequency range when the determination is performed by determining whether the frequency is included in the specific frequency range, and any of the power supply side frequencies are included in the specific frequency range. It determines with the object electromagnetic noise of a side frequency having a possibility of affecting the operation | movement by the said specific apparatus in the said specific frequency. The power supply control apparatus characterized by the above-mentioned. The power supply control device according to any one of claims 1 to 5 ,
The determination unit (20) includes at least one of a predetermined specified center frequency within the switching frequency variation range and each n-th order specified center frequency n times the specified center frequency (n is a natural number of 2 or more). One of the power supply side specified center frequencies, and the specific frequency is a predetermined frequency band including the power supply side specified center frequency for each of the at least one power supply side specified center frequency. When the specific frequency is included in any one of the power supply side specified bands, the power supply side included in the power supply side specified band is determined. It is determined that the target electromagnetic noise having a frequency closest to a specified center frequency may affect the operation of the specific device at the specific frequency. Power control device.