JP7160658B2 - DC power supply and power control method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a DC power supply device and a power control method, and more particularly to a technique for stabilizing an output voltage.

For example, a general vehicle that constitutes a freight train cannot receive power supply from the outside of the vehicle such as an overhead wire or a power supply car. However, even in such a vehicle, there is a need to mount electronic equipment for detecting the state of the vehicle, etc., and it is necessary to procure power supply power necessary to operate the electronic equipment. Therefore, by mounting an axle generator on the axle of the vehicle, it is possible to secure the necessary power supply power from the output of this axle generator.

However, in such a generator, the state of power generation fluctuates over a wide range according to the running speed of the vehicle, that is, the rotational speed of the axle. In other words, it is difficult to secure a sufficiently high voltage in a low speed running state of about several [km/h], and conversely, in a normal running state of about several tens [km/h], a too high voltage of 100 [V] or more is output. In addition, if the generator is designed so that a sufficiently high voltage can be obtained even at low speeds, the voltage output during normal running will become too high.

Moreover, not only in the case of freight trains, but also in the case of, for example, wind power generators, the state of power generation greatly fluctuates as the wind speed fluctuates, and the output voltage fluctuates. Therefore, when using the generator as described above, it is assumed that a DC power supply device having a function of stabilizing the output voltage is connected to the output of the generator.

Further, for example, in an electric vehicle (EV), a DC power supply is used to secure the low-voltage power supply power required by on-vehicle electronic devices from an on-vehicle power supply that outputs a high voltage of about 200 to 400 [V]. There is also a possibility that it will be

The types of DC power supply devices as described above are divided into two types, a series regulator and a switching regulator, depending on the structural difference in generating the required output voltage. A series regulator generates a necessary voltage drop by using a transistor or the like connected in series with the current path inside the regulator to generate a stable output voltage that is lower than the input voltage.

A switching regulator can generate a target output voltage by periodically turning on and off a switching element such as a transistor to adjust the average value of output power. Further, there are pulse width modulation (PWM) and pulse frequency modulation (PFM) depending on the switching method.

For example, the switching power supply circuit of Patent Document 1 uses a technique for realizing a smooth control mode transition by reducing the ripple voltage when shifting from PFM control under light load to PWM control under heavy load. showing. Moreover, the switching power supply control circuit of Patent Document 2 shows a technique for switching between a plurality of control methods with a relatively simple operation without increasing the circuit scale.

JP-A-2008-92712 JP 2015-130722 A

For example, when extracting power from the output of an axle generator on a freight train and trying to procure DC power of about 5 to 12 [V] required by loads such as general electronic equipment, DC power supply The potential difference between the input and output of the device fluctuates in a wide range from several [V] to 100 [V] or more.

When using a DC power supply in such an environment, in the case of a series regulator, the power loss in the step-down transistor becomes extremely large, resulting in an increase in wasteful power consumption and the amount of heat generated in proportion to the loss. increases.

In the case of a switching regulator, for example, by adopting the techniques of Patent Documents 1 and 2, two types of control, pulse width modulation and pulse frequency modulation, can be selectively used. In the case of pulse width modulation, since the on-time and off-time of the pulse repeats at a constant cycle, it is easy to remove the switching noise that occurs, but on the other hand, the loss associated with switching is reduced because there are many switching times even at light loads. is difficult. In the case of pulse frequency modulation, conversely, when the load is light, the number of times of switching decreases, which makes it easier to reduce loss. Also, when an inductor, that is, an electric coil is used for purposes such as noise removal, reactive power is generated, making control difficult.

Therefore, by selectively using two types of control, pulse width modulation and pulse frequency modulation, as in Patent Documents 1 and 2, loss can be easily reduced under both heavy load and light load conditions. Become. However, when switching between the PWM operation mode and the PFM operation mode, ripples in the output voltage may increase, or the mode transition may take a long time, resulting in a decrease in voltage stability. Furthermore, even if either the PWM operation mode or the PFM operation mode is selected, precise power control cannot be performed due to limitations in control. For example, in the PWM operation mode, it is possible to adjust the time width during which the switching element is turned on within a constant control period. Since it is not possible to allocate a different OFF section in the middle, fine adjustments cannot be made.

For example, when power is extracted from the output of an axle generator on a freight train and switched inside the DC power supply to supply power to the load, the DC power supply supplies as much energy as possible to the output in the low speed range of the train. It is desirable to be able to control the transmission. Also, when the vehicle is traveling at a steady speed and the axle generator is outputting very high voltage, it is desirable that the DC power supply transfer only a fraction of the input energy to the output. In addition, in response to fluctuations in the voltage output by the axle generator and changes in the energy consumed by the load, the DC power supply appropriately adjusts the amount of energy transferred from the input to the output, thereby reducing the voltage supplied to the load. It is desirable to be able to reduce the ripple of Also, in situations such as when the load is light, it is desirable to reduce the number of times of switching to reduce the loss inside the DC power supply.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and its object is to properly follow the fluctuations and increase the loss even in an environment where the input voltage fluctuations and the load fluctuations are very large. It is an object of the present invention to provide a direct-current power supply device and a power control method that can suppress the noise and easily maintain the output voltage in a stable state.

In order to achieve the above object, the DC power supply device and power control method according to the present invention are characterized by the following (1) to ( 6 ).
(1) A direct-current power supply that performs a switching operation based on input power with an uncertain voltage supplied from a predetermined power supply source, and generates output power in which voltage changes are suppressed at least compared to the input power. There is
a pulse modulation unit having a function of simultaneously performing an operation of adjusting the ratio of the ON time and the OFF time in the switching operation and an operation of adjusting the frequency of the switching operation;
with
The pulse modulation unit includes a PWM control unit that adjusts the ratio of ON time and OFF time in one cycle section of the switching operation, a PFM control unit that adjusts the length of one cycle section of the switching operation, and the PWM a thinning control unit that turns off the switching operation at least part of the timing during the ON time of the control unit;
The thinning control unit reflects a change in a voltage detection value of at least one of the input power and the output power in the switching operation.
A DC power supply device characterized by:

According to the DC power supply device having the above configuration (1), since switching of the operation mode is unnecessary, it is possible to avoid the output voltage from becoming unstable due to the switching of the operation mode. That is, it is possible to continuously and continuously adjust the ratio of the ON time to the OFF time in the switching operation and the frequency, in response to fluctuations in the input voltage and fluctuations in the load over a wide range. The output voltage can be kept stable without causing a large increase in loss. Moreover, since control combining adjustment of the ratio of ON time and OFF time in switching operation and adjustment of frequency is performed simultaneously, it is possible to widen the adjustable range and perform precise power control. Also, by combining a plurality of controls, it is possible to avoid fixing the control period. That is, since the frequency spectrum of noise generated by switching is spread over a wide range, there is no need to connect an inductor or the like to remove noise of a specific frequency.
Furthermore, according to the DC power supply device having the configuration of (1) above, for example, even when the PWM control cycle is lengthened to reduce the loss and the number of switching times per unit time is reduced, switching is performed as necessary by thinning control. can be thinned out and the switching cycle can be adjusted. Therefore, it is possible to control the power precisely against fluctuations in the input voltage and the load while suppressing an increase in switching loss.

(2) a result obtained by converting the voltage detection value of at least one of the input power and the output power in accordance with a predetermined nonlinear characteristic, at least one of the ratio of the ON time to the OFF time in the switching operation and the frequency of the switching operation; having a non-linear transformation that reflects on
The DC power supply device according to (1) above, characterized in that:

According to the DC power supply device having the configuration of (2) above, the control necessary for suppressing the increase in loss due to switching and stabilizing the output power is performed with respect to the fluctuation of the input voltage and the fluctuation of the output voltage. can be done easily. For example, when a freight train is running at low speed, it is desirable to reduce the potential difference between the input and output of the DC power supply to accelerate the rise of the voltage applied to the load. Appropriate control can be easily performed for each area, such as areas where internal switching loss needs to be reduced, and where it is desirable to speed up the response speed of the DC power supply in response to sudden changes in load. Become.

( 3 ) having a mute control section that reflects a result of comparing the voltage detection value of the output power with predetermined upper and lower limit values in the operation of the pulse modulation section;
The DC power supply device according to the above (1) or (2) , characterized by:

According to the DC power supply device having the configuration ( 3 ) above, pulse modulation control can be performed by distinguishing between, for example, a state in which the output voltage is stable and a state other than that. As a result, when the output voltage is already stable, it is possible to suppress unnecessary control and stabilize the operation.

( 4 ) Power control for performing a switching operation based on input power with an uncertain voltage supplied from a predetermined power supply source, and generating output power in which voltage changes are suppressed at least compared to the input power. a method,
Simultaneously performing a first operation of adjusting the ratio of the ON time and the OFF time in the switching operation and a second operation of adjusting the frequency of the switching operation,
reflecting a voltage change in at least one of the input power and the output power in at least one of the first operation and the second operation;
Continuously or sequentially determining a first control amount representing the ratio of the ON time to the OFF time in one cycle section of the switching operation;
Continuously or sequentially determining a second control amount representing the length of one cycle section of the switching operation;
Continuously or sequentially determining a third control amount for turning off the switching operation at least part of the timing during the ON time according to the first control amount;
Simultaneously reflecting the first controlled variable, the second controlled variable, and the third controlled variable in the switching operation with respect to a change in the voltage detection value of at least one of the input power and the output power;
A power control method characterized by:

According to the power control method having the configuration ( 4 ), it is unnecessary to switch the operation mode, so that it is possible to avoid the output voltage becoming unstable due to the switching of the operation mode. That is, it is possible to continuously and continuously adjust the ratio of the ON time to the OFF time in the switching operation and the frequency, in response to fluctuations in the input voltage and fluctuations in the load over a wide range. The output voltage can be kept stable without causing a large increase in loss. Moreover, since control combining adjustment of the ratio of ON time and OFF time in switching operation and adjustment of frequency is performed simultaneously, it is possible to widen the adjustable range and perform precise power control. Moreover, it is possible to avoid fixing the control period by combining a plurality of controls. That is, since the frequency spectrum of noise generated by switching is spread over a wide range, there is no need to connect an inductor or the like to remove noise of a specific frequency.
Furthermore, according to the power control method having the configuration (4), even when the PWM control period is lengthened to reduce the loss, for example, and the number of switching times per unit time is reduced, switching is performed as necessary by thinning control. can be thinned out and the switching cycle can be adjusted. Therefore, it is possible to perform precise power control against fluctuations in input voltage and load while suppressing an increase in switching loss.

( 5 ) A result obtained by converting the voltage detection value of at least one of the input power and the output power in accordance with a predetermined nonlinear characteristic is used as at least one of the ratio of the ON time to the OFF time in the switching operation and the frequency of the switching operation. to reflect in
The power control method according to ( 4 ) above, characterized in that:

According to the power control method having the configuration ( 5 ) above, control necessary for suppressing an increase in loss due to switching and stabilizing the output power is performed with respect to fluctuations in the input voltage and the fluctuations in the output voltage. can be done easily. For example, when a freight train is running at low speed, it is desirable to reduce the potential difference between the input and output of the DC power supply to accelerate the rise of the voltage applied to the load. Appropriate control can be easily performed for each area, such as areas where internal switching loss needs to be reduced, and where it is desirable to speed up the response speed of the DC power supply in response to sudden changes in load. Become.

( 6 ) comparing the voltage detection value of the output power with a predetermined upper limit value and a predetermined lower limit value, and reflecting the result of the comparison in the switching operation;
The power control method according to the above (4) or (5) , characterized by:

According to the power control method having the configuration ( 6 ) above, pulse modulation control can be performed by distinguishing between, for example, a state in which the output voltage is stable and a state other than that. As a result, when the output voltage is already stable, it is possible to suppress unnecessary control and stabilize the operation.

According to the DC power supply and the power control method of the present invention, even in an environment where the input voltage fluctuates or the load fluctuates significantly, the fluctuations are appropriately followed to suppress the increase in loss, and the output It becomes easier to keep the voltage stable. In particular, since it is not necessary to switch the operation mode, it is possible to prevent the output voltage from becoming unstable and the voltage ripple from increasing due to the switching of the operation mode.

The present invention has been briefly described above. Furthermore, the details of the present invention will be further clarified by reading the following detailed description of the invention (hereinafter referred to as "embodiment") with reference to the accompanying drawings. .

FIG. 1 is a block diagram showing a configuration example of a DC power supply device according to an embodiment of the present invention. FIG. 2 is a graph showing an example of input/output characteristics of the nonlinear signal converter. FIGS. 3(a) and 3(b) are waveform diagrams showing examples of three signals with different input voltages. FIGS. 4(a) and 4(b) are waveform diagrams showing examples of four signals when the input voltages are the same. FIGS. 5(a) and 5(b) are waveform diagrams showing examples of three signals when the input voltage is the same and the loads are different.

Specific embodiments relating to the present invention will be described below with reference to each drawing.

<Configuration example of DC power supply>
FIG. 1 shows a configuration example of a DC power supply device according to an embodiment of the present invention.

The power supply device 10 shown in FIG. 1 is used to take in the input power Pin as a power source from the output of the generator 20, stabilize it, and supply it to the load 21 as the output power Pout. As a specific example, it is assumed that the generator 20 is an axle generator mounted on a freight train or the like, a wind power generator, or a high-voltage power supply mounted on an electric vehicle or the like. The load 21 is assumed to be an electronic device mounted on the vehicle, a portable electronic device carried by each passenger, or the like.

If the generator 20 is an axle generator, the voltage of the input power Pin will vary over a wide range of 0 to 100 [V] or more as the running speed of the vehicle fluctuates. Further, it is desired that the load 21 is supplied with the necessary electric power even in an environment immediately after the vehicle starts running at a low speed of about several [km/h], for example. Also, the power supply device 10 needs to be controlled so that an excessive voltage is not output to the load 21 even in an environment where the voltage of the input power Pin is 100 [V].

Therefore, for example, when the voltage of the output power Pout to be supplied to the load 21 is 12 [V], the potential difference between the input power Pin and the output power Pout in the power supply device 10 is within a wide range of about 0 to 100 [V]. Expected to change. Since the power supply device 10 basically constitutes a switching regulator, even if the potential difference between the input and output becomes large, it is possible to reduce the loss and heat generated inside. However, in general, when the switching period is relatively short, precise power control is difficult, and when the switching period becomes short, there is a tendency for the loss associated with switching to increase sharply.

In addition, when the current of the output power Pout fluctuates with the on/off of the load 21, the voltage of the output power Pout changes. need to do

In addition, unless the environment allows the use of a stable external power supply, etc., the power supply power required for operating each circuit inside the power supply device 10 also needs to be generated by taking in the input power Pin. In other words, immediately after the vehicle starts to move, the power supply 10 itself is also in a stopped state. , the load 21 can be supplied with an output power Pout of sufficient voltage.

A power supply device 10 shown in FIG. and a starting circuit 19 .

Note that each function of the nonlinear signal converter 12, the voltage controller 13, the pulse controller 14, and the mute controller 17 is realized using an analog electronic circuit such as an operational amplifier in this embodiment. Of course, it is possible to replace these functions with general logic circuits or computer processing, but it is more advantageous to use analog electronic circuits in terms of response speed when the power supply voltage rises.

The power input unit 11 is a circuit for taking in the input power Pin output from the generator 20 and generating the DC input power P0. For example, when the input power Pin is AC power, the rectifier circuit inside the power input unit 11 rectifies the AC and converts it into a DC voltage. Moreover, when there are a plurality of power supply sources, the power input unit 11 selectively takes in the input power Pin from any one of the plurality of power supply sources.

The nonlinear signal converter 12 converts the voltage of the signal SG1 into the voltage of the signal SG2 according to the desired nonlinear conversion characteristics (see FIG. 2). This makes it easy to achieve appropriate control characteristics in consideration of the variation range of the DC input power P0, the variation range of the potential difference between the input power Pin and the output power Pout, the variation range of the load 21, and the like. Alternatively, the signal SG6 fed back from the output side of the control system may be input to the nonlinear signal converter 12 and the voltage of the signal SG6 may be reflected in the signal SG2.

The voltage control section 13 generates the voltage of the signal SG3 required for controlling the pulse control section 14 based on the two signals SG2 and SG6. The voltage of the signal SG3 is a threshold value used when the pulse control section 14 internally generates a pulse by pulse width modulation or the like.

The pulse controller 14 includes a PWM controller 14a, a PFM controller 14b, a thinning controller 14c, and an output pulse generator 14d. If the PFM control unit 14b takes over the function of the thinning control unit 14c, the thinning control unit 14c can be omitted.

The PWM control unit 14a performs control for pulse width modulation (PWM) capable of automatically adjusting the ratio between the ON-state time width and the OFF-state time width for each control cycle. The control cycle in the PWM control section 14a may be fixed in advance, or may be automatically adjusted. In practice, an analog comparator in the PWM control unit 14a compares a triangular wave signal generated by an oscillator (not shown) inside the pulse control unit 14 with a threshold value corresponding to the voltage of the signal SG3, thereby reducing the output of the signal SG31. A pulse is generated.

The PFM control unit 14b is an analog circuit for generating a pulse signal, which is pulse frequency modulated (PFM) according to the voltage of the signal SG3, as the signal SG32. The output of the PFM control unit 14b may be reflected in the control cycle of the PWM control unit 14a to make the control cycle variable.

The thinning control unit 14c irregularly thins out the time so that the actual ON time of the PWM pulse generated by the PWM control unit 14a is shortened in the period in which the pulse is turned on, or when the PWM pulse is turned off. A signal SG33 is generated for inserting another pulse into another interval as required.

The output pulse generation unit 14d performs processing such as addition, subtraction, and logic operation on the signals SG31, SG32, and SG33 output by the PWM control unit 14a, the PFM control unit 14b, and the thinning control unit 14c, respectively, and synthesizes them. The result is output as signal SG4. Therefore, the pulse signal appearing in the signal SG4 is a combination of the pulse generated by PWM control, the pulse generated by PFM control, and the thinning control output.

If the frequency corresponding to the control cycle of PWM control and the frequency of PFM control are different, the effect of the pulse of signal SG32 appears irregularly at the timing of the pulse-on period and the pulse-off period of signal SG31. That is, when the PWM control unit 14a and the PFM control unit 14b operate simultaneously, the PFM control unit 14b performs the same operation as the thinning control unit 14c, so the thinning control unit 14c becomes unnecessary.

In any case, in the signal SG4 output by the output pulse generator 14d, in addition to the pulse width modulated pulse generated by the PWM controller 14a, there is another pulse generated by the PFM controller 14b or the thinning controller 14c. appears irregularly. Further, the frequency of the pulses appearing irregularly is automatically adjusted by the PFM control section 14b according to the voltage of the signal SG3.

The power switch circuit 15 includes a high-power semiconductor switching device capable of controlling ON/OFF of energization. can be supplied to the load 21 side. That is, the average value of the power supplied to the load 21 side is adjusted according to the on/off time ratio of the pulse in the signal SG4.

As a specific example of the semiconductor switching device that constitutes the main part of the power switch circuit 15, it is assumed that N-channel MOSFET, GaNFET, and SiCFET are employed. Thereby, the efficiency of switching can be improved.

The rectifier circuit 16 has a function of limiting the direction of current flowing through the power supply line on the output side of the power switch circuit 15 .
The mute control unit 17 feeds back the signal SG5 appearing on the output side of the rectifier circuit 16 to the input side of the control system, forming a control loop to achieve stable operation as a whole. In this embodiment, the signal SG6 output from the mute control unit 17 mutes the threshold value used by the pulse control unit 14 for pulse generation depending on the situation.

The mute controller 17 includes a voltage upper limit detector 17a, a voltage lower limit detector 17b, and a calculator 17c. The voltage upper limit detector 17a compares the voltage of the signal SG5 with the upper limit voltage of a window provided in the expected voltage change range of the signal SG5 using an analog comparator, and indicates whether or not the upper limit voltage is exceeded. Output a signal. The voltage lower limit detector 17b compares the lower limit voltage of the window with the voltage of the signal SG5 using an analog comparator, and outputs a signal indicating whether or not the voltage is equal to or higher than the lower limit voltage. Operation unit 17c performs operation on the output signal of voltage upper limit detection unit 17a and the output signal of voltage lower limit detection unit 17b to generate signal SG6.
The mute control unit 17 can apply feedback to the control system of the power supply device 10 with a signal SG6 so as to limit the operation only within the range of the window.

The power output circuit 18 performs control for further stabilizing the output power Pout supplied to the load 21 . The power output circuit 18 has, for example, a circuit for limiting the output of excessive voltage and a circuit for limiting the flow of excessive current to the output.

The activation circuit 19 is a signal for activating the energization operation of the power switch circuit 15 in a linear region where the pulse control unit 14 is not yet operating, such as when the voltage of the DC input power P0 rises from 0 [V]. to generate

<Example of nonlinear conversion characteristics>
FIG. 2 shows an example of input/output characteristics of the nonlinear signal converter 12. In FIG. In FIG. 2, the horizontal axis corresponds to the input voltage [V], ie the voltage of the signal SG1, and the vertical axis corresponds to the output voltage [V], ie the voltage of the signal SG2.

As shown in FIG. 2, in the nonlinear signal converter 12, the relationship between the input voltage and the output voltage is nonlinear. For example, when the input voltage is in the range of about 0 to 35 [V], the output voltage is about 11 [V] and there is almost no change. Further, when the input voltage is within the range of about 45 to 90 [V], the output voltage decreases in inverse proportion to the increase in the input voltage. Also, in the range where the input voltage is 95 [V] or higher, the slope of the change in the output voltage with respect to the change in the input voltage is gentle.

<Explanation of characteristic operation>
In power supply device 10 shown in FIG. 1, PWM control section 14a and PFM control section 14b provided in pulse control section 14 operate simultaneously, and the result is reflected in the pulse of signal SG4. In other words, the switching operation of the power switch circuit 15 is performed in accordance with pulses generated as a result of simultaneously performing two types of control, PWM and PFM, or three types of control including the thinning control section 14c.

By performing PWM and PFM at the same time, even if the control period of PWM is constant, another pulse is randomly generated between multiple periodic pulses generated by PWM, or a pulse generated by PWM is generated at random. A pulse appears in the signal SG4 such that the time width of the ON section of the pulse is randomly thinned out.

Therefore, even if the PWM control cycle is not shortened to increase the switching frequency in the power switch circuit 15 in the steady state, PFM pulses are inserted as necessary or the PWM pulse time width is thinned out to achieve precise control. Power control can be realized. Loss caused by switching can be reduced by lengthening the PWM control cycle. In addition, by randomly changing the generation cycle of the pulse used for switching, the peak position in the frequency spectrum of noise generated as unwanted radiation can be spread over a wide range, facilitating noise countermeasures.

In the power supply device 10 shown in FIG. 1, the voltage of the DC input power P0 is converted by the nonlinear signal conversion section 12 so as to be controlled according to the nonlinear characteristics and is input to the pulse control section 14 . In other words, the relationship between the input voltage of the signal SG1 and the signal SG3 input to the pulse control section 14 as the threshold voltage becomes nonlinear.

This facilitates designing the power supply 10 to operate with desired control characteristics. For example, in a region where the voltage of the DC input power P0 is 35 [V] or less, the rise of the output power Pout can be hastened by bringing the potential difference between the DC input power P0 and the output power Pout close to 0 [V]. Therefore, in this region, by setting the voltage of the signal SG2 output by the nonlinear signal converter 12 to about 11 [V], the operation of the pulse controller 14 is stopped and the power switch circuit 15 is turned on ( conduction) state.

Further, in a region where the voltage of the DC input power P0 is in the range of about 40 to 90 [V], the excess energy is reduced by switching the power switch circuit 15 . Therefore, an appropriate voltage is output as the signal SG2, and the voltage of the signal SG3 input to the pulse control unit 14 as the threshold voltage is adjusted. As a result, pulses generated by PWM and PFM control are applied to the control input of power switch circuit 15 as signal SG4.

Further, by feeding back the voltage of the signal SG5 on the output side of the power switch circuit 15 to the input side of the pulse control unit 14, the voltages of the signal SG5 and the output power Pout are close to the target predetermined voltage, for example, 12 [V]. The pulse control unit 14 automatically performs control so as to stabilize the state.

Further, when the voltage of the signal SG5 is within the range of the window, the operation of the pulse control section 14 is restricted by the signal SG6 output from the mute control section 17, and the control state at that time is maintained. Then, when the voltage of the signal SG5 exceeds the upper limit voltage of the window or becomes equal to or lower than the lower limit voltage of the window, the automatic control of the pulse control unit 14 is resumed, and the voltage approaches the range of the window by the control of PWM and PFM. The voltage of signal SG5 is adjusted.

In any case, the simultaneous control of the PWM control section 14a and the PFM control section 14b can make the control characteristics of the pulse control section 14 variable. That is, in accordance with the potential difference between the DC input power P0 and the output power Pout, the switching loss generated inside the power supply device 10 is appropriately reduced, and the pulse signal is such that the voltage of the output power Pout is appropriately maintained. It can be output as SG4.

In addition, since the nonlinear signal conversion unit 12 is used, the voltage of the signal SG3 used as the threshold voltage by the pulse control unit 14 is set appropriately according to the desired nonlinear characteristics according to the potential difference between the DC input power P0 and the output power Pout. can be automatically adjusted to In addition, since the nonlinear signal conversion unit 12 can be used to make the input/output relationship linear in the control of the power supply device 10 in a region where the voltage of the DC input power P0 is low, the occurrence of hysteresis in the input/output relationship can be avoided. can be done.

With the above-described control, it is possible to follow not only the voltage change of the DC input power P0 but also the rapid fluctuation of the current flowing through the load 21 so that the voltage of the output power Pout can be appropriately controlled to be stabilized. Moreover, switching loss inside the power supply device 10 can be reduced, and heat generation can be suppressed.

In practice, the single control characteristic of the PWM control section 14a can be designed to cope with changes in the pulse time width (ON time) of about a fraction [sec] to several [μsec]. In addition, the single control characteristic of the PFM control section 14b can be designed to handle frequency changes in the range of about several hundred [Hz] from the DC level.

<Specific examples of operating waveforms>
<Waveform change according to input voltage change>
Examples of three signals with different input voltages are shown in FIGS. 3(a) and 3(b). In FIGS. 3A and 3B, the horizontal axis represents time and the vertical axis represents voltage. Note that the position of 0 on the vertical axis of each signal is made different so that each waveform can be easily grasped.

Each of the signals SG4, SG6, and SG30 shown in FIG. 3(a) represents each waveform when the voltage of the DC input power P0 is 40.5 [V]. Further, each of the signals SG4, SG6, and SG30 in FIG. 3(b) represents each waveform when the voltage of the DC input power P0 is 111 [V]. Also, the signal SG30 is generated by an oscillator included inside the pulse control unit 14 . The waveform of the signal SG30 is a triangular wave, and is used as a base signal for the PWM control section 14a to generate a pulse of the signal SG4 by PWM control. In FIGS. 3A and 3B, the frequency corresponding to one cycle of signal SG30 is approximately 390 [Hz].

In the state shown in FIG. 3(a), pulses are generated in the signals SG4 and SG6 at intervals of about 27 [msec] (37 [Hz]). The ratio of intervals is very large. That is, since the power switch circuit 15 is in the ON state over almost the entire section, most of the energy of the DC input power P0 passes through the power switch circuit 15 and is supplied to the load 21 as the output power Pout.

That is, in a region where the voltage of the DC input power P0 is low, the voltage of the signal SG2 output from the nonlinear signal converter 12 increases due to the characteristics shown in FIG. A pulse appears in signal SG4. This pulse is significantly different from a general PWM signal generated based on the period of the base signal SG30.

On the other hand, in the state shown in FIG. 3(b), pulses appear in the signal SG4 at a shorter cycle than in FIG. 3(a). However, as shown in FIG. 3(b), the pulse of the signal SG4 does not appear every cycle of the base signal SG30, but irregularly. In other words, PWM pulses are thinned irregularly. Moreover, the time width of the high level section of the pulse of the signal SG4 is shorter than the width of the high level section of the signal SG6. Also, there is a portion where a plurality of pulses are generated in one section in which the signal SG6 is at high level.

By generating the pulses of signal SG4 as shown in FIGS. 3(a) and 3(b), fine power control can be achieved over a wide range of input voltages. In this case, the pulse for switching the power switch circuit 15 is not generated repeatedly at a constant period unlike general PWM, so the frequency of switching can be reduced and the power loss can be reduced. Also, since the switching cycle is irregular, it is easy to take measures against radiation noise.

<Waveform when input voltage is intermediate level>
Examples of four signals when the voltage of the DC input power P0 is 74 [V] are shown in FIGS. 4(a) and 4(b). In FIGS. 4A and 4B, the horizontal axis represents time and the vertical axis represents voltage. Note that the position of 0 on the vertical axis of each signal is made different so that each waveform can be easily grasped.

Also in the examples shown in FIGS. 4A and 4B, pulses frequently appear in the signal SG4. However, the control period of the pulse in the signal SG4 is not constant, and the time width of the ON section in which the pulse is at high level also slightly fluctuates for each period. That is, thinning of pulses generated by the PWM control unit 14a and thinning of the ON time width of each pulse are performed.

For example, when the voltage of the signal SG5 rises too much, the pulse control unit 14 performs control during the interval in which the signal SG6 fed back is at high level to thin out the pulses to be output to the signal SG4 and the ON time width. can be thinned out. Thereby, the voltage of the signal SG5 can be lowered.

<Waveform change according to load change>
Examples of three signals with the same input voltage (approximately 62 [V]) and different loads are shown in FIGS. 5(a) and 5(b). In FIGS. 5A and 5B, the horizontal axis represents time and the vertical axis represents voltage. Also, FIG. 5(a) represents a state in which the impedance of the load 21 is 50 [Ω], and FIG. 5(b) represents a state in which the impedance of the load 21 is 25 [Ω].

That is, in the state of FIG. 5(b), the current flowing through the load 21 is significantly increased as compared with the state of FIG. 5(a). do.

Therefore, as shown in FIG. 5(b), the appearance frequency of the pulses appearing in the signal SG4, that is, the frequency, is greatly increased compared to FIG. 5(a). As a result, the frequency with which the power switch circuit 15 is energized also increases, making it possible to supplement the power required by the load 21 in a short period of time. This state appears in the waveform change of the signal SG5 in FIGS. 5(a) and 5(b). In other words, such control can suppress an increase in voltage ripple when the load increases.

<Advantages of Power Supply Device 10>
In the power supply device 10 shown in FIG. 1, the result of simultaneous operation of the PWM control section 14a and the PFM control section 14b in the pulse control section 14 can be reflected in the output signal SG4 of the output pulse generating section 14d. Therefore, there is no need to switch between PWM and PFM modes, and it is possible to prevent the voltage and current of the output power Pout from becoming unstable due to the switching.

Moreover, since the pulse frequency of the signal SG4 for switching the power switch circuit 15 varies, the spectrum of unnecessary radiation is spread over a wide band. Therefore, noise peaks do not occur at specific frequencies, and noise countermeasures are facilitated. Also, there is no need to connect electrical coils to reduce noise, and no reactive power is generated.

It should be noted that the control contents of the power supply device 10 shown in FIG. 1 can be replaced with the operation of a logic circuit or replaced with software processing of a computer. When using a computer or the like, for example, in order to speed up the startup of the control operation when the generator 20 is started, a special external power supply is prepared or a storage battery is used so that the computer can always operate. It is also assumed that the state is kept on standby.

Here, the features of the DC power supply device and the power control method according to the embodiments of the present invention described above are briefly summarized in [1] to [8] below.
[1] A switching operation is performed based on input power (DC input power P0) with an uncertain voltage supplied from a power supply source (generator 20), and voltage changes are suppressed at least as compared to the input power. A DC power supply (power supply 10) that generates output power,
A function (output pulse generator 14d) that simultaneously performs an operation for adjusting the ratio of the ON time and the OFF time in the switching operation (PWM control unit 14a) and an operation for adjusting the frequency of the switching operation (PFM control unit 14b). a pulse modulation unit (pulse control unit 14),
A DC power supply device comprising:

[2] A result obtained by converting the voltage detection value of at least one of the input power and the output power in accordance with a predetermined nonlinear characteristic is used as at least one of the ratio of the ON time to the OFF time in the switching operation and the frequency of the switching operation. having a nonlinear conversion unit (nonlinear signal conversion unit 12) that reflects
The DC power supply device according to [1] above, characterized in that:

[3] The pulse modulation section includes a PWM control section (14a) that adjusts the ratio of ON time and OFF time in one cycle section of the switching operation, and a PFM control section (14a) that adjusts the length of one cycle section of the switching operation. a control unit (14b); and a thinning control unit (14c) that turns off the switching operation at least partly during the ON time of the PWM control unit,
The thinning control unit reflects a change in a voltage detection value of at least one of the input power and the output power in the switching operation.
The DC power supply device according to the above [1] or [2], characterized by:

[4] A mute control section (17) that reflects a result of comparing the voltage detection value of the output power with predetermined upper and lower limit values in the operation of the pulse modulation section;
The DC power supply device according to any one of [1] to [3], characterized by:

[5] A power control method for performing a switching operation based on input power with an uncertain voltage supplied from a power supply source, and for generating output power in which voltage changes are suppressed at least compared to the input power. There is
Simultaneously performing a first operation (PWM control unit 14a) for adjusting the ratio of ON time and OFF time in the switching operation and a second operation (PFM control unit 14b) for adjusting the frequency of the switching operation,
A voltage change of at least one of the input power and the output power is reflected in at least one of the first operation and the second operation;
A power control method characterized by:

[6] A result obtained by converting the voltage detection value of at least one of the input power and the output power in accordance with a predetermined nonlinear characteristic is used as at least one of the ratio of the ON time to the OFF time in the switching operation and the frequency of the switching operation. to reflect in
The power control method according to [5] above, characterized in that:

[7] Continuously or sequentially determining a first control amount representing the ratio of the ON time to the OFF time in one cycle section of the switching operation;
Continuously or sequentially determining a second control amount representing the length of one cycle section of the switching operation;
Continuously or sequentially determining a third control amount for turning off the switching operation at least part of the timing during the ON time according to the first control amount;
Simultaneously reflecting the first controlled variable, the second controlled variable, and the third controlled variable in the switching operation with respect to a change in the voltage detection value of at least one of the input power and the output power;
The power control method according to the above [5] or [6], characterized by:

[8] comparing the voltage detection value of the output power with a predetermined upper limit value and a lower limit value, respectively, and reflecting the result of the comparison in the switching operation;
The power control method according to any one of the above [5] to [7], characterized by:

REFERENCE SIGNS LIST 10 power supply device 11 power input unit 12 nonlinear signal conversion unit 13 voltage control unit 14 pulse control unit 14a PWM control unit 14b PFM control unit 14c thinning control unit 14d output pulse generation unit 15 power switch circuit 16 rectifier circuit 17 mute control unit 17a voltage Upper limit detection unit 17b Voltage lower limit detection unit 17c Operation unit 18 Power output circuit 19 Starting circuit 20 Generator 21 Load Pin Input power P0 DC input power Pout Output power P1, P2 Power SG1, SG2, SG3, SG4, SG5, SG6 Signal

Claims (6)

A DC power supply that performs a switching operation based on input power with an uncertain voltage supplied from a power supply source, and generates output power in which voltage changes are suppressed at least compared to the input power,
a pulse modulation unit having a function of simultaneously performing an operation of adjusting the ratio of the ON time and the OFF time in the switching operation and an operation of adjusting the frequency of the switching operation;
with
The pulse modulation unit includes a PWM control unit that adjusts the ratio of ON time and OFF time in one cycle section of the switching operation, a PFM control unit that adjusts the length of one cycle section of the switching operation, and the PWM a thinning control unit that turns off the switching operation at least part of the timing during the ON time of the control unit;
The thinning control unit reflects a change in a voltage detection value of at least one of the input power and the output power in the switching operation.
A DC power supply device characterized by: A result of converting the voltage detection value of at least one of the input power and the output power according to a predetermined non-linear characteristic is reflected in at least one of a ratio of ON time to OFF time in the switching operation and a frequency of the switching operation. having a nonlinear conversion unit,
2. The DC power supply device according to claim 1, characterized in that: a mute control unit that reflects a result of comparing the voltage detection value of the output power with predetermined upper and lower limits in the operation of the pulse modulation unit;
3. The DC power supply device according to claim 1 or 2 , characterized in that: A power control method for performing a switching operation based on input power with an uncertain voltage supplied from a power supply source, and generating output power in which a change in voltage is suppressed at least as compared to the input power,
Simultaneously performing a first operation of adjusting the ratio of the ON time and the OFF time in the switching operation and a second operation of adjusting the frequency of the switching operation,
reflecting a voltage change in at least one of the input power and the output power in at least one of the first operation and the second operation;
Continuously or sequentially determining a first control amount representing the ratio of the ON time to the OFF time in one cycle section of the switching operation;
Continuously or sequentially determining a second control amount representing the length of one cycle section of the switching operation;
Continuously or sequentially determining a third control amount for turning off the switching operation at least part of the timing during the ON time according to the first control amount;
Simultaneously reflecting the first controlled variable, the second controlled variable, and the third controlled variable in the switching operation with respect to a change in the voltage detection value of at least one of the input power and the output power;
A power control method characterized by: A result of converting the voltage detection value of at least one of the input power and the output power according to a predetermined non-linear characteristic is reflected in at least one of a ratio of ON time to OFF time in the switching operation and a frequency of the switching operation. ,
5. The power control method according to claim 4 , characterized in that: comparing the voltage detection value of the output power with a predetermined upper limit value and a lower limit value, respectively, and reflecting the result of the comparison in the switching operation;
6. The power control method according to claim 4 or 5 , characterized in that:

Images