Multiphase power supply

Abstract

A multiphase power supply device is provided to prevent the continuous or cumulative imbalance of output power caused by switching frequency changes, and to improve operational reliability. The multiphase power supply device (1) includes: first to Nth DC-DC converters (4-7) connected in parallel; and a switching control unit (8) configured to supply first to Nth PWM signals (S1-S4) and perform interleaved control on the first to Nth DC-DC converters. At the beginning of a certain period of the first PWM signal (S1), the switching frequency of the first PWM signal (S1) is changed (the period is changed to T2). The length of the initial period (T2-D, T2-2×D, T2-3×D) of the kth PWM signal (S2, S3, S4) after the change of time point is shorter than the length of the period after the next period of the initial period of the kth PWM signal after the change of time point (T2).

Description

Technical Field

[0001] This invention relates to a multiphase power supply device for use in various electronic devices. Background Technology

[0002] In conventional multiphase power supply systems, pulse signals used to turn the switching elements in each power supply unit on and off are used for output control. PWM (Pulse Width Modulation) control is performed by setting the duration of the pulse signal (on duty cycle) and the period without the pulse signal (off duty cycle) within one cycle at a given switching frequency. Furthermore, the ratio of the on to off duty cycle in the PWM control (duty cycle) is continuously adjusted based on the voltage, current, and other parameters of the power supply unit's output, thereby enabling continuous control to achieve the target output power of the power supply unit.

[0003] Noise is radiated from the power supply unit due to the repeated on / off control of the switching elements. To minimize the impact of radiated noise on surrounding electronic equipment, spread spectrum control is implemented to vary the switching frequency of the PWM signal within a given range as a countermeasure to suppress radiated noise. This suppresses radiated noise generated at specific frequencies, thereby minimizing the impact of radiated noise on surrounding electronic equipment.

[0004] Conventional multiphase power supply devices are disclosed, for example, in Patent Document 1.

[0005] Prior art literature

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2010-252513 Summary of the Invention

[0008] The multiphase power supply device includes: first to Nth DC-DC converters (N being an integer of 2 or more), connected in parallel between the input and output terminals; and a switching control unit configured to supply pulse width modulation (PWM) signals from the first to Nth DC-DC converters respectively, and to perform interleaved control on the first to Nth DC-DC converters. At a change time point at the beginning of a certain cycle of the first PWM signal, the switching frequency of the first PWM signal is changed. The length of the initial cycle of the kth PWM signal after the change time point is made shorter than the length of the subsequent cycles following the initial cycle of the kth PWM signal after the change time point.

[0009] This multiphase power supply device has high reliability. Attached Figure Description

[0010] Figure 1This is a circuit block diagram of the multiphase power supply device in the implementation method.

[0011] Figure 2 This is a circuit block diagram of the multiphase power supply device in the implementation method.

[0012] Figure 3 This is a timing diagram showing the normal operating state of the multiphase power supply device in the implementation method.

[0013] Figure 4 This is a timing diagram showing the frequency variation state of the multiphase power supply device in the implementation method.

[0014] Figure 5 This is a timing diagram showing the frequency variation state of the multiphase power supply device in the implementation method.

[0015] Figure 6 This is a timing diagram of a comparative example multiphase power supply device. Detailed Implementation

[0016] Figure 1 This is a circuit block diagram of the multiphase power supply device 1 in the embodiment. The multiphase power supply device 1 includes an input terminal 2, an output terminal 3, a first-phase DC-DC converter 4, a second-phase DC-DC converter 5, a third-phase DC-DC converter 6, a fourth-phase DC-DC converter 7, and a switch control unit 8. Here, as an example, the method of setting the number of phases N to 4 and installing the DC-DC converters in the multiphase power supply device 1 is used for explanation, but the value of the number of phases N is an integer greater than or equal to 2. DC-DC converters 4 to 7 are connected to the input terminal 2 and the output terminal 3, and are connected in parallel between the input terminal 2 and the output terminal 3. That is, the input terminal 42 of DC-DC converter 4, the input terminal 52 of DC-DC converter 5, the input terminal 62 of DC-DC converter 6, and the input terminal 72 of DC-DC converter 7 are connected to the input terminal 2. The output terminals 43 of DC-DC converter 4, 53 of DC-DC converter 5, 63 of DC-DC converter 6, and 73 of DC-DC converter 7 are connected to the output terminal 3. The input terminal 2 is configured to be connected to a DC power supply P1. Output terminal 3 is configured to be connected to load L1.

[0017] The switch control unit 8 sends a pulse width modulation (PWM) signal S1 to control the operation of the first-phase DC-DC converter 4, a PWM signal S2 to control the operation of the second-phase DC-DC converter 5, a PWM signal S3 to control the operation of the third-phase DC-DC converter 6, and a PWM signal S4 to control the operation of the fourth-phase DC-DC converter 7. The phase of PWM signal S2 is delayed by 90° compared to PWM signal S1, the phase of PWM signal S3 is delayed by 90° compared to PWM signal S2, and the phase of PWM signal S4 is delayed by 90° compared to PWM signal S3. In other words, in this embodiment, the number of phases N is 4, therefore, the PWM signals S1, S2, S3, and S4 have a phase difference of 90° (π / 2), obtained by dividing 360° (2π) by the number of phases N, and the first-phase DC-DC converter 4, the second-phase DC-DC converter 5, the third-phase DC-DC converter 6, and the fourth-phase DC-DC converter 7 are controlled to perform interleaved operations.

[0018] When the switching frequency of PWM signals S1 to S4 changes from the first frequency f1 to the second frequency f2, the switching control unit 8 sets a differential time D (=Tp / N). The differential time is the value obtained by subtracting the period T2 of the second frequency f2 from the period T1 of the first frequency f1, and dividing it by the number of phases N. Using the differential time D, the switching control unit 8 shortens the period of the first cycle of the PWM signals S2 supplied to the DC-DC converters 5 to 7 immediately after the switching frequency change by a time D starting from period T2; shortens the period of the first cycle of the PWM signal S3 by 2×D starting from period T2; and shortens the period of the first cycle of the PWM signal S4 by 3×D starting from period T2. Using the full number of phases N, in other words, the period of the first cycle of the PWM signals S2 to S4 changes sequentially from period T2, shortening the time from the second phase's time D to the product of the time D and (N-1) in the Nth phase. In other words, in the first cycle immediately following the change of the switching frequency, the periods of PWM signals S1, S2, S3, and S4 are all different values.

[0019] Then, after the second cycle of the PWM signals S1 to S4 after the switching frequency is changed, the pulse width control circuit 13 sends PWM signals S1 to S4 with a 90° phase difference between the rising edges of their duty cycles. Here, PWM signals S1 to S4 have the same period T2 at the second frequency f2 and are sent to control the operation of the first-phase DC-DC converter 4, the second-phase DC-DC converter 5, the third-phase DC-DC converter 6, and the fourth-phase DC-DC converter 7. Using the entire number of phases N, in other words, the rising edges of the duty cycles of the PWM signals from the first to the Nth phases have a phase difference equal to the value obtained by dividing 360° by the number of phases N. Furthermore, the PWM signals from the first to the Nth phases have the same period at the second frequency f2 and are sent to control the operation of the DC-DC converters from the first to the Nth phases.

[0020] Through the above structure and operation, during spread spectrum control, the period of output power imbalance among DC-DC converters 4, 5, 6, and 7 caused by the switching frequency changing from the first frequency f1 to the second frequency f2 is limited to a short period after the switching frequency is switched. Therefore, the continuous or cumulative output power imbalance can be prevented. As a result, the operational reliability of the multiphase power supply unit 1 can be improved.

[0021] The operation of the multiphase power supply device 1 in the following embodiment will be described in detail. Figure 2 This is a circuit block diagram of multiphase power supply device 1. Figure 3 This is a timing diagram of the normal operating state of the multiphase power supply device 1.

[0022] The multiphase power supply unit 1 includes an input terminal 2, an output terminal 3, a first-phase DC-DC converter 4, a second-phase DC-DC converter 5, a third-phase DC-DC converter 6, a fourth-phase DC-DC converter 7, and a switch control unit 8. As an example, this is described using a configuration where the number of phases N is set to 4 and the DC-DC converters for phases 1 through 4 are arranged in the multiphase power supply unit 1; however, the number of phases N can be an integer greater than or equal to 2. Furthermore, the multiple DC-DC converters 4 through 7 arranged in parallel can all be buck converters, or the multiple DC-DC converters 4 through 7 can all be boost converters.

[0023] The first-phase DC-DC converter 4, the second-phase DC-DC converter 5, the third-phase DC-DC converter 6, and the fourth-phase DC-DC converter 7 are connected to input terminal 2 and output terminal 3, and are connected in parallel to each other between input terminal 2 and output terminal 3. Furthermore, the first-phase DC-DC converter 4 is provided with a first switching element 9, the second-phase DC-DC converter 5 is provided with a second switching element 10, the third-phase DC-DC converter 6 is provided with a third switching element 11, and the fourth-phase DC-DC converter 7 is provided with a fourth switching element 12.

[0024] The first switching element 9, the second switching element 10, the third switching element 11, and the fourth switching element 12 can be semiconductor elements that have substantially the same characteristics. For example, FETs (field-effect transistors) and IGBTs (insulated-gate bipolar transistors) can be used as semiconductor elements.

[0025] The switch control unit 8 includes a pulse width control circuit 13, a frequency control circuit 14, a spread spectrum circuit 15, a detection circuit 16, and an arithmetic circuit 17. The pulse width control circuit 13 sends a PWM signal S1 to control the on / off operation of the first switch element 9, a PWM signal S2 to control the on / off operation of the second switch element 10, a PWM signal S3 to control the on / off operation of the third switch element 11, and a PWM signal S4 to control the on / off operation of the fourth switch element 12. The frequency control circuit 14 controls the frequency of the PWM signals S1 to S4. The spread spectrum circuit 15 performs control to vary the frequency of the PWM signals S1 to S4.

[0026] As long as the switching frequency can be varied to reduce radiated noise, there is no need to specifically limit the frequency variation control implemented by the spread spectrum circuit 15. Variation control can be, for example, linear control in which the frequency changes approximately linearly within a given period, sinusoidal control in which the frequency changes approximately sinusoidally within a given period, or random control in which the amplitude and period of variation change irregularly within a given range by using random numbers, etc.

[0027] The period from when the switching frequency changes from a certain value to a lower value in stages. In other words, as an example, the duration of the first frequency f1 until the switching frequency switches from the first frequency f1 to the second frequency f2, and the subsequent duration of the second frequency f2, is defined as the length of the period of the PWM signals S1 to S4. The duration of the first frequency f1 and the second frequency f2 includes multiple periods of the PWM signals S1 to S4.

[0028] PWM signals S1, S2, S3, and S4 are transmitted from the pulse width control circuit 13. The phase of PWM signal S2 is delayed by 90° compared to PWM signal S1, the phase of PWM signal S3 is delayed by 90° compared to PWM signal S2, and the phase of PWM signal S4 is delayed by 90° compared to PWM signal S3. In other words, the number of phases N in this embodiment is 4, therefore the PWM signals S1, S2, S3, and S4 have a phase difference of 90° (π / 2), obtained by dividing 360° (2π) by the number of phases N. The first-phase DC-DC converter 4, the second-phase DC-DC converter 5, the third-phase DC-DC converter 6, and the fourth-phase DC-DC converter 7 are controlled to perform interleaved operation.

[0029] Figure 2 The timing diagram shown is for the multiphase power supply unit 1 under normal operation. Figure 3 The timing diagram for the normal operating state, where the normal operating state refers to the state where the first-phase DC-DC converter 4, the second-phase DC-DC converter 5, the third-phase DC-DC converter 6, and the fourth-phase DC-DC converter 7, which have substantially the same characteristics and are connected in parallel, are controlled by PWM signals S1 to S4 with the same switching frequency, and are set to a state where the switching frequency does not change with time. Furthermore, in Figure 3 In the timing diagram of the normal operating state, for ease of explanation, we take the case where the duty cycle of PWM signals S1 to S4 is 0.5 as an example. The duty cycle of PWM signals S1 to S4 can be varied as needed. The duty cycle of PWM signals S1 to S4 is determined by the following steps. For example, the voltage and current detected at input terminal 2 and output terminal 3 are detected by the detection circuit 16 of the switch control unit 8, and the information detected by the detection circuit 16 is transmitted to the arithmetic circuit 17 of the switch control unit 8. Then, the arithmetic circuit 17 performs calculations such as comparison with the target output voltage, output current, or output power, and determines the duty cycle of PWM signals S1 to S4 based on the calculation results.

[0030] exist Figure 3The diagram shows PWM signals S1 to S4 at a first frequency f1, which are the same switching frequency. The period of the PWM signals S1 to S4 corresponding to the first frequency f1 is set to the first period T1. Furthermore, PWM signal S1 is plotted as a curve corresponding to the PWM signal controlling the operation of the first switching element 9 of the first-phase DC-DC converter 4; PWM signal S2 is plotted as a curve corresponding to the PWM signal controlling the operation of the second switching element 10 of the second-phase DC-DC converter 5; PWM signal S3 is plotted as a curve corresponding to the PWM signal controlling the operation of the third switching element 11 of the third-phase DC-DC converter 6; and PWM signal S4 is plotted as a curve corresponding to the PWM signal controlling the operation of the fourth switching element 12 of the fourth-phase DC-DC converter 7. The first-phase DC-DC converter 4, the second-phase DC-DC converter 5, the third-phase DC-DC converter 6, and the fourth-phase DC-DC converter 7 operate with a phase difference of 90° (π / 2), obtained by dividing 360° (2π) by the number of phases N (=4). Figure 3 The diagram shows PWM signals S1 to S4 at the same switching frequency f1. The period of the PWM signals S1 to S4 corresponding to the first frequency f1 is set as the first period T1.

[0031] Under normal operating conditions, multiple converters with substantially the same characteristics are connected in parallel and operate at the same switching frequency and with the same duty cycle. Thus, with the first-phase DC-DC converter 4, the second-phase DC-DC converter 5, the third-phase DC-DC converter 6, and the fourth-phase DC-DC converter 7 all bearing substantially equal power loads, power is supplied to the load (not shown) connected to output terminal 3.

[0032] Next, use Figure 4The operation of the multiphase power supply unit 1 will be explained in detail using a first timing diagram of the switching frequency change state of the multiphase power supply unit in an embodiment of the present invention. In this embodiment, for ease of explanation, two states are used: a normal state and a frequency change state. This is to clarify the relationship between the changes in the switching frequency, and because the switching frequency generally changes continuously in a repeating manner for each given period when the multiphase power supply unit 1 is actually operating. Therefore, the normal state can be described as the state where the switching frequency is the first frequency, and the frequency change state can be described as the state where the switching frequency shifts from the first frequency to the second frequency. Therefore, the operation when the switching frequency switches from the first frequency f1 to the second frequency f2 will be explained below. Furthermore, the transmission of the frequency change signal Sc implemented by the spread spectrum circuit 15 can be performed, for example, by satisfying given operating conditions such as a given time after the multiphase power supply unit 1 starts up, or after the multiphase power supply unit 1 starts up and the output stabilizes. Moreover, the timing of transmitting the frequency change signal Sc can be pre-stored in the switch control unit 8 along with threshold values ​​for the aforementioned conditions.

[0033] Here, a frequency change signal Sc is first sent from the spread spectrum circuit 15 to the frequency control circuit 14. The frequency change signal Sc is used to change the frequency of the PWM signals S1 to S4, which are the switching frequencies, from the first frequency f1 to the second frequency f2. For example, if the frequency change signal Sc is sent at time point t00, the switching of the frequency of the PWM signal S1 for the first switching element 9 of the first phase DC-DC converter 4 begins. For ease of explanation, this is shown as an example starting from the switching of the frequency of the first phase DC-DC converter 4. Generally, the first phase can be set to the phase whose timing of the rise of the PWM signals S1 to S4 after time point t00 is the earliest, or the frequency switching can be performed earliest for a specific phase. Furthermore, time point t00 may not be set to be necessarily consistent with the timing of the rise of the PWM signal S1 as in time point t11.

[0034] By sending a frequency change signal Sc, the frequency of the PWM signal S1 switches from the first frequency f1 to the second frequency f2 at time point t11. In other words, in the first-phase DC-DC converter 4, the period of the PWM signal S1 corresponding to the first frequency f1 switches from T1 to the period T2 corresponding to the second frequency f2.

[0035] Furthermore, in response to the transmission of the frequency change signal Sc, the operational circuit 17 sets the differential time D, which is the value obtained by dividing the differential period Tp, which corresponds to the periodic displacement when the switching frequency changes from the first frequency f1 to the second frequency f2, by the number of phases N. Here, the differential period Tp corresponds to T1-T2, and the differential time D is Tp / N.

[0036] Then, further, the pulse width control circuit 13 uses differential time D to cause the first cycle of the PWM signals S2 to S4, which occur immediately after the frequency change signal Sc is sent, to change sequentially. If through... Figure 4 To explain sequentially, in the first-phase DC-DC converter 4, at time t11 when the switching frequency changes from the first frequency f1 to the second frequency f2, as described previously, the period of the PWM signal S1 changes from T1 to T2. Next, when the switching frequency of the second-phase DC-DC converter 5 changes from the first frequency f1 to the second frequency f2 with a phase delay of 90° compared to the first-phase DC-DC converter 4, the period of the PWM signal S2, which rises from off to on, changes from T1 to T2-D at time t12. Furthermore, when the switching frequency of the third-phase DC-DC converter 6 changes from the first frequency f1 to the second frequency f2 with a phase delay of 90° compared to the second-phase DC-DC converter 5, the period of the PWM signal S3, which rises from off to on, changes from T1 to T2-2×D at time t13. Furthermore, when the switching frequency of the fourth-phase DC-DC converter 7 switches from the first frequency f1 to the second frequency f2 with a phase delay of 90° compared to the third-phase DC-DC converter 6, the period of the rising PWM signal S4 from off to on at time t14 switches from T1 to T2-3×D. Using all phases N, in other words, the length of the first period of the PWM signals S2 to SN changes sequentially from the differential time D in the second phase to the product of D and (N-1) in the Nth phase.

[0037] Then, after the second cycle of the PWM signals S1 to S4 following the transmission of the frequency change signal Sc from the frequency control circuit 14, the pulse width control circuit 13 transmits PWM signals S1 to S4, each with a 90° phase difference between the rising edges of the duty cycle, starting from time points Ta, Tb, Tc, and Td within a period T2 corresponding to the switching frequency of the second frequency f2. In other words, from the second cycle of the PWM signals S1 to S4 after the transmission of the frequency change signal Sc until the subsequent transmission of a further frequency change signal Sc, the time points Ta, Tb, Tc, and Td maintain a 90° phase difference.

[0038] exist Figure 4In the embodiment of the timing diagram shown, in PWM signals S2 to S4, the length of the period that changes from T2-D, T2-2×D, to T2-3×D immediately after the frequency change signal Sc is sent is kept constant at T2 in the second period. However, for example, taking the second-phase DC-DC converter 5 as an example, it is set to change from T2-D to T2 in the first period from t12 to t22 and in the second period of PWM signal S2. Although not shown here, it can also be in the following manner: from the first period to the third period and the fourth period, the length of the period changes in stages across multiple periods, changing from T2-D to T2. Although the explanation is omitted here, for PWM signals S3 and S4, the period can also change in stages across multiple periods.

[0039] Using the full number of phases N, in other words, after the second cycle following the switching frequency change from the first frequency f1 to the second frequency f2, the rising edges of the duty cycles of the PWM signals S1 to SN of phases 1 to N successively have a phase difference obtained by dividing 360° by the number of phases N. Furthermore, this is sent from the pulse width control circuit 13 so that there is a T2 with the same period at the second frequency f2, thereby controlling the DC-DC converters of phases 1 to N.

[0040] Furthermore, in this embodiment Figure 4 In this example, the second switching frequency f2 is shown to be a value greater than the first frequency f1. Therefore, the period T1 is a value greater than the period T2. Furthermore, the differential period Tp is defined as the periodic displacement, i.e., T1-T2, during the switching frequency change from the first frequency f1 to the second frequency f2. Further, the differential time D is set to Tp / N. Moreover, for example, for the second-phase DC-DC converter 5, the first period is varied in a way that shortens the period to T2-D. Therefore, in... Figure 4 In the example shown, T1-T2 are positive values, and the value of Tp / N is also positive. Similarly, for the third-phase DC-DC converter 6, the cycle is changed in the first cycle to shorten the cycle to T2-2×D, and for the fourth-phase DC-DC converter 7, the cycle is changed in the first cycle to shorten the cycle to T2-3×D.

[0041] In other words, when the first frequency f1 is lower than the second frequency f2, the period of the second-phase DC-DC converter 5 to the fourth-phase DC-DC converter 7 is temporarily shortened when the switching frequency changes. On the other hand, when the first frequency f1 is higher than the second frequency f2, the values ​​of T1-T2 and D become negative. In the second-phase DC-DC converter 5, the value of T2-D becomes greater than T2, and the period when the switching frequency changes is temporarily extended. Of course, the same applies to the third-phase DC-DC converter 6 and the fourth-phase DC-DC converter 7, changing in a way that extends the period sequentially.

[0042] As described above, the period during which the switching frequency changes from a low value to a high value is temporarily shortened. As a shortening step, for example, in the second-phase DC-DC converter 5, without shortening the period and keeping T1 constant, the timing of the rising edge of the turn-on time is delayed from the time point t20, which should have risen, to the time point t12 by a time delay equivalent to the absolute value of the differential time D. This shortens the time of the first cycle from T2 to T2-D. Here, D is a positive value.

[0043] On the other hand, such as Figure 5 As shown in the second timing diagram of the switching frequency change state of the multiphase power supply device in the embodiment of the present invention, the period when the switching frequency changes from a high value to a low value is changed by temporarily extending it. As an extension step, for example, in the second-phase DC-DC converter 5, while keeping T1 constant without extending the period, the period is delayed from the time point t200, which should have fallen, to the time point t112, where the switching duty cycle from the falling edge of the turn-on time to the turn-off duty cycle, by a time delay equivalent to the absolute value of the differential time D, thereby extending the time of the first cycle from T2 to T2-D. Here, D is a negative value. Similarly, for the third-phase DC-DC converter 6, the period is changed in the first cycle to extend to T2-2×D, and for the fourth-phase DC-DC converter 7, the period is changed in the first cycle to extend to T2-3×D. Here, D is also a negative value.

[0044] In the control described in the above embodiments, when the switching frequency is increased, if the rising edge time of the on-duty cycle is delayed, the on-duty cycle period is shortened and the off-duty cycle period is set to T2 / 2. As a result, the period after the switching frequency is switched is shortened. However, it is also possible that when the period after the switching frequency is shortened, after the rising edge time of the on-duty cycle is delayed, the on-duty cycle period is set to T2 / 2 and the off-duty cycle period is shortened. As a result, the period after the switching frequency is switched is shortened.

[0045] Furthermore, in the control described in the above embodiments, when the switching frequency is reduced, after delaying the switching time from the on-duty cycle to the off-duty cycle, the on-duty cycle period is extended, and the off-duty cycle period is set to T2 / 2. As a result, the period after the switching frequency is switched is extended. However, it is also possible that when the period after the switching frequency is extended, the off-duty cycle period is extended after setting the on-duty cycle period to T2 / 2. As a result, the period after the switching frequency is switched is extended.

[0046] In the aforementioned conventional multiphase power supply devices, where the period is not shortened or lengthened when the switching frequency is changed, as described in the above embodiments, and the power supply device employing converters is controlled in a multiphase structure, the outputs of each converter become inconsistent due to the switching frequency switching during spread spectrum control, resulting in current imbalance between the converters. By repeatedly switching the switching frequency, this current imbalance between converters accumulates and increases, thus raising concerns about decreased operational reliability of the power supply device.

[0047] Figure 6 This is a timing diagram of a comparative multiphase power supply unit, equivalent to a conventional multiphase power supply unit that does not undergo periodic adjustments. For example... Figure 6 As shown, in the comparative example of the multiphase power supply device, the initial phase difference cannot be maintained after the frequency changes, and therefore proper interleaving cannot be performed. The current imbalance between the converters accumulates and increases, thus causing concerns about the reduced reliability of the power supply device.

[0048] In the above embodiments, for ease of explanation, the pulse width control circuit 13, frequency control circuit 14, spread spectrum circuit 15, detection circuit 16, and arithmetic circuit 17 each have individual functions, and the switch control unit 8 is configured to include these circuits. However, it is also possible not to differentiate the functions of the pulse width control circuit 13, frequency control circuit 14, spread spectrum circuit 15, detection circuit 16, and arithmetic circuit 17, and instead have the switch control unit 8 have both detection and control functions. Furthermore, it is also possible that the pulse width control circuit 13, frequency control circuit 14, spread spectrum circuit 15, detection circuit 16, and arithmetic circuit 17 are not housed in a single, encapsulated switch control unit 8, and can be distributed throughout the multiphase power supply device 1.

[0049] When the length of the first cycle of the PWM signals S2 to S4 in the second-phase DC-DC converters 5 to 4-phase DC-DC converters 7 immediately following the transmission of the frequency change signal Sc is varied, as explained above, the duration of the first cycle of the PWM signals S2 to S4 is varied by shortening or lengthening the on-duty cycle period. Alternatively, the off-duty cycle period can be shortened or lengthened to shorten or lengthen the first cycle of the PWM signals S2 to S4.

[0050] pass Figure 4 This section explains the steps for shortening the first cycle of the PWM signals S2 to S4 when the switching frequency increases. In the second-phase DC-DC converter 5, while keeping T1 unchanged without shortening the cycle, the timing of the rising edge of the turn-on time is delayed from the expected rising time point t20 to time point t12 by a time delay equivalent to the absolute value of the differential time D. Furthermore, after setting the turn-on duty cycle period to T2 / 2, the turn-off duty cycle period is shortened to T2 / 2-D, thus shortening the first cycle time from T2 to T2-D. In the third-phase DC-DC converter 6, while keeping T1 unchanged without shortening the cycle, the timing of the rising edge of the turn-on time is delayed from the expected rising time point by a time delay equivalent to the absolute value of the differential time 2×D. Furthermore, after setting the turn-on duty cycle period to T2 / 2, the turn-off duty cycle period is shortened to T2 / 2-2×D, thus shortening the first cycle time from T2 to T2-2×D. In the 4th phase DC-DC converter 7, without shortening the period and keeping T1 unchanged, the timing of the rising edge of the turn-on time is delayed by a time equivalent to the absolute value of the differential time 3×D from the point when it should rise. Furthermore, after setting the turn-on duty cycle period to T2 / 2, the turn-off duty cycle period is shortened to T2 / 2-3×D, thus shortening the time of the first cycle from T2 to T2-3×D.

[0051] On the other hand, through Figure 5 This section explains the steps for extending the first cycle of the PWM signals S2 to S4 when the switching frequency decreases. In the second-phase DC-DC converter 5, the period is T2 / 2, and the on-duty cycle is maintained until time point t200. Then, at time point t200, the on-duty cycle is switched to the off-duty cycle. Moreover, the off-duty cycle is maintained for a period from time point t200 to T2 / 2-D. Thus, the time of the first cycle is extended from T2 to T2-D. Here, D is a negative value. Similarly, for the third-phase DC-DC converter 6, the first cycle is extended to T2-2×D, and for the fourth-phase DC-DC converter 7, the first cycle is extended to T2-3×D. Here, D is a negative value.

[0052] In other words, in the first cycle immediately following the change of the switching frequency, in order to set the periods of PWM signals S1, S2, S3, and S4 to different values, the off duty cycle periods of PWM signals S1 to S4 can be made the same for each other, and the on duty cycle periods can be different for each other; or the on duty cycle periods of PWM signals S1 to S4 can be the same for each other, and the off duty cycle periods can be different for each other; or the on duty cycle periods of PWM signals S1 to S4 can be different for each other, and the off duty cycle periods can be different for each other.

[0053] Thus, the multiphase power supply unit 1 includes first to Nth DC-DC converters 4 to 7 (N is an integer greater than or equal to 2, and is 4 in this embodiment) connected in parallel between the input terminal 2 and the output terminal 3. The multiphase power supply unit 1 also includes a switching control unit 8, which is configured to supply the first to Nth pulse width modulation (PWM) signals S1 to S4 to the first to Nth DC-DC converters 4 to 7 respectively, and to perform interleaved control on the first to Nth DC-DC converters 4 to 7. The phase of the kth PWM signal among the first to Nth PWM signals S1 to S4 is delayed by a phase difference of 360° / N compared to the (k-1)th PWM signal (k is any integer satisfying 2≤k≤N). At the switching time point tch at the beginning of a certain period of the first PWM signal S1, the switching control unit 8 changes the switching frequency of the first PWM signal S1 from a first frequency f1 to a second frequency f2. The switch control unit 8 obtains the differential time D (=(T1-T2) / N) by dividing the differential period obtained by subtracting the period T2 of the second frequency f2 from the period T1 of the first frequency f1 by N. The switch control unit 8 sets the length of the initial period of the k-th PWM signal (S2~S4) after the change time point tch to T2-D×(k-1). The switch control unit 8 sets the length of the period after the initial period of the k-th PWM signal (S2~S4) after the change time point tch to the period T2.

[0054] Furthermore, after the duty cycle of the PWM signals S2-S4 immediately following the transmission of the frequency change signal Sc is made consistent with the duty cycle of the PWM signal S1, the period of the PWM signals S2-S4 can be shortened or lengthened. In other words, the duration of the first cycle of the PWM signals S2-S4 immediately following the transmission of the frequency change signal Sc can also be shortened or lengthened by shortening or lengthening both the on and off duty cycles.

[0055] Symbol Explanation

[0056] 1: Multiphase power supply unit

[0057] 2: Input end

[0058] 3: Output end

[0059] 4: DC-DC converter

[0060] 5: DC-DC converter

[0061] 6: DC-DC converter

[0062] 7: DC-DC converter

[0063] 8: Switch Control Section

[0064] 9: Switching elements

[0065] 10: Switching elements

[0066] 11: Switching elements

[0067] 12: Switching elements

[0068] 13: Pulse Width Control Circuit

[0069] 14: Frequency control circuit

[0070] 15: Spread spectrum circuit

[0071] 16: Detection Circuit

[0072] 17: Operational circuit.

Claims

1. A multiphase power supply device, comprising: Input terminal; Output terminal; Multiple DC-DC converters are configured in parallel between the input and the output, consisting of phases 1 to N; and Switch control unit, The switch control unit is configured such that, A pulse width modulation (PWM) signal, having a phase difference (360° divided by the number of phases N), is transmitted to interleave the operation of the DC-DC converters from the first phase to the Nth phase. Change the switching frequency of the PWM signal from the first frequency to the second frequency. The differential time D is defined as the differential period from the first frequency to the second frequency divided by the number of phases N of the plurality of DC-DC converters. The first cycle of the PWM signal from the second phase to the Nth phase immediately following the change of the switching frequency is sequentially varied from the differential time D in the second phase to the product of D and (N-1) in the Nth phase, and then transmitted. After the second cycle following the change of the switching frequency, PWM signals for phases 1 to N are sent such that after the rising edge of the duty cycle has a phase difference obtained by dividing 360° by N, there is the same period at the second frequency, and the operation of the DC-DC converters for phases 1 to N is controlled.

2. The multiphase power supply device according to claim 1, wherein, The switching control unit is configured to send PWM signals from the first phase to the Nth phase in the second cycle after the switching frequency is changed, so that after the rising edge of the duty cycle has a phase difference obtained by dividing 360° by the number of phases N, there is the same period at the second frequency, and the operation of the DC-DC converter from the first phase to the Nth phase is controlled.

3. The multiphase power supply device according to claim 1, wherein, The switch control unit has: A pulse width control circuit sends multiple PWM signals for the first to Nth phases to the switching elements of the DC-DC converters to control the on / off operation of the switching elements. A frequency control circuit controls the switching frequency of the PWM signal; A spread spectrum circuit is used to vary the switching frequency. The detection circuit is capable of detecting the voltage at the output terminal; and The arithmetic circuit uses the information detected by the detection circuit to perform calculations such as comparisons with output voltage, output current, or output power, and determines the duty cycle of the PWM signal based on the calculation results.

4. The multiphase power supply device according to claim 3, wherein, The switch control unit is configured such that, The rising edge of the duty cycle of the PWM signals from the second phase to the Nth phase immediately following the transmission of the frequency change signal from the spread spectrum circuit is sequentially changed from the differential time D in the second phase to the product of D and (N-1) in the Nth phase. The first cycle of the PWM signal from the second phase to the Nth phase immediately following the change of the switching frequency is changed sequentially from the differential time D in the second phase to the product of D and (N-1) in the Nth phase and then transmitted.

5. The multiphase power supply device according to claim 3, wherein, The switching control unit is configured such that when a frequency change signal is sent from the spread spectrum circuit and the switching frequency increases, The rising edge of the duty cycle of the PWM signals from the second phase to the Nth phase immediately following the transmission of the frequency change signal is changed sequentially from the time of the absolute value of D in the second phase to the time of the absolute value of the product of D and (N-1) in the Nth phase. After the switching frequency is changed, the first cycle of the PWM signal from the second phase to the Nth phase is sequentially shortened until the time from the differential time D in the second phase to the product of D and (N-1) in the Nth phase is transmitted. The switch control unit is configured such that when the frequency change signal is sent and the switch frequency decreases, The switching of the PWM signals from the second phase to the Nth phase immediately following the transmission of the frequency change signal, from the on-duty cycle to the off-duty cycle, is sequentially changed from the time of the absolute value of D in the second phase to the time of the absolute value of the product of D and (N-1) in the Nth phase. The first period of the PWM signal from the second phase to the Nth phase immediately following the change of the switching frequency is extended sequentially from the differential time D in the second phase to the product of D and (N-1) in the Nth phase and then transmitted.

6. The multiphase power supply device according to claim 3, wherein, The switch control unit is configured such that, The switching of the PWM signals from the second phase to the Nth phase immediately following the transmission of the frequency change signal from the spread spectrum circuit, from the on-duty cycle to the off-duty cycle, is sequentially changed from the differential time D in the second phase to the product of D and (N-1) in the Nth phase. The first period of the PWM signal from the second phase to the Nth phase immediately following the change of the switching frequency is changed sequentially from the differential time D in the second phase to the product of D and (N-1) in the Nth phase.

7. A multiphase power supply device, comprising: Input terminal; Output terminal; The first to Nth DC-DC converters are connected in parallel between the input and the output, where N is an integer greater than or equal to 2; and The switching control unit is configured to supply pulse width modulation (PWM) signals of the first to Nth values ​​to the first to Nth DC-DC converters respectively, and to perform interleaved control on the first to Nth DC-DC converters. The phase difference between the k-th PWM signal and the (k-1)-th PWM signal is 360° / N, where k is any integer satisfying 2≤k≤N. The switch control unit is configured such that, At a change time point at the beginning of a certain cycle of the first PWM signal, the switching frequency of the first PWM signal is changed from the first frequency to the second frequency. The differential time D is obtained by dividing the differential period (obtained by subtracting the period T2 of the second frequency from the period T1 of the first frequency) by N. The differential time D = (T1 - T2) / N. The length of the initial period of the k-th PWM signal after the change time point is set to T2-D×(k-1). The length of the period following the initial period of the k-th PWM signal after the changed time point is set as the period T2.

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