JP2017093009A - Switching power supply device and power conversion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve both stable power supply output, and electric wave adaptability of radiation noise suppression.SOLUTION: A switching power supply device comprises: a voltage converter that has a semiconductor switching element, and a coil and a capacitor for stabilizing a voltage, and generates and feeds a desired output voltage by on/off-control of the semiconductor switching element; a voltage controller that calculates an ON time period or an OFF time period of the semiconductor switching element within a switching frequency, and outputs a control signal for on/off-controlling the semiconductor switching element; and a frequency diffusion controller that determines whether or not diffusion control of the switching frequency is required to be performed on the basis of monitoring results of a state of a load circuit or a DC power supply. The voltage controller performs the diffusion control of the switching frequency in a case where a diffusion control permission signal is received from the frequency diffusion controller.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a switching power supply device that obtains a desired output voltage by performing step-down operation or step-up operation by controlling on / off of a semiconductor switching element, and in particular, switching for spreading a switching frequency for the purpose of suppressing radiation noise. The present invention relates to a power supply device and a power conversion device.

  Conventionally, a method of diffusing a switching frequency has been proposed in order to suppress radiation noise associated with driving of a semiconductor switching element (see, for example, Patent Document 1). Japanese Patent Laid-Open No. 2004-228620 proposes a method for solving problems such as deterioration of radiation noise and increase in heat generation of a filter coil by stopping frequency spread control during the startup period and the stop period of the switching control device.

Japanese Patent No. 5772020

However, the prior art has the following problems.
In the case of having an integrated circuit such as a microcomputer or ASIC including a communication circuit with another device as a load of the switching power supply device, the microcomputer or ASIC is connected via communication only when necessary to reduce power consumption. A method such as starting is considered. Accordingly, in such a case, the load current greatly changes even after the switching power supply is started.

  In general, a switching power supply at light load tends to be unstable. Therefore, if the frequency spread control is performed when such an unstable state occurs, the output of the switching power supply may oscillate.

  Furthermore, some switching power supply devices obtain a desired output voltage not only by a step-down operation but also by a step-up operation. Generally, the step-up operation has lower power conversion efficiency than the step-down operation, and the power supply capability is reduced. Therefore, when performing frequency spread control in the boost operation, the output voltage may become unstable.

  The present invention has been made to solve such a problem, and an object of the present invention is to obtain a switching power supply power converter capable of achieving both stable power output and radio wave compatibility by suppressing radiation noise. To do.

  A switching power supply apparatus according to the present invention generates a desired output voltage by performing voltage conversion on a power supply voltage from a DC power supply, and supplies the desired output voltage to a load circuit connected downstream. The semiconductor switching element has a coil and a capacitor for stabilizing the voltage, and the semiconductor switching element is controlled to be turned on / off in accordance with a control signal, thereby performing a step-down operation or a step-up operation as voltage conversion. Based on at least one information of a voltage conversion unit that generates and supplies a desired output voltage, and a power supply voltage from a DC power supply, an output voltage of the voltage conversion unit, or a current flowing through a coil, within a switching frequency Control for calculating ON / OFF time of semiconductor switching element and controlling ON / OFF of semiconductor switching element The voltage control unit that outputs a signal and the frequency spread control unit that determines whether or not the switching frequency spread control is necessary based on the monitoring result of the load circuit or DC power supply state and outputs a spread control permission signal or a spread control prohibition signal When the voltage control unit receives the spread control permission signal from the frequency spread control unit, the voltage control unit executes the spread frequency spread control and outputs the control signal generated based on the spread control switching frequency. To do.

  In addition, the power conversion device according to the present invention is a DC power supply in which a plurality of phase bridge circuits in which power semiconductor switching elements are connected in series to form upper and lower arms are connected in parallel, and both ends of the phase bridge circuit are chargeable / dischargeable. By connecting the bridge circuit in which the connection point between the power semiconductor switching elements of the upper and lower arms of the phase bridge circuit is connected to the AC terminal of the armature winding of the multiphase rotating electrical machine, and switching control of the bridge circuit, the AC− A power conversion device including a bridge control unit that executes DC power conversion control or DC-AC power conversion control, wherein the bridge circuit uses the switching power supply device of the present invention, and the switching frequency diffusion control is required. Judgment is made and switching control of the power semiconductor switching element is executed.

  According to the present invention, the switching frequency for PWM control of the semiconductor switching element is configured to permit or prohibit the diffusion control of the switching frequency based on the state of the DC power supply or the load circuit. Therefore, frequency spreading can be prevented when the power supply output is unstable, or power supply output can be prevented from becoming unstable due to frequency spreading, and stable power supply to the load circuit can be achieved. Furthermore, radiation noise can be suppressed by performing frequency spreading control. As a result, it is possible to obtain a switching power supply device and a power conversion device capable of achieving both stable power output and radio wave compatibility by suppressing radiation noise.

It is a block diagram which shows the structure of the switching power supply which concerns on Embodiment 1 of this invention. It is the figure which showed the specific structural example of the voltage converter in the switching power supply which concerns on Embodiment 1 of this invention. It is a figure which shows an example of the triangular wave generation circuit of the voltage control part in the switching power supply device which concerns on Embodiment 1 of this invention. It is a figure which shows an example of the frequency spreading | diffusion control part 7 in the switching power supply device which concerns on Embodiment 1 of this invention. It is a timing chart of the frequency spreading | diffusion control part 7 in the switching power supply which concerns on Embodiment 1 of this invention. It is a figure which shows another example of the frequency spreading | diffusion control part 7 in the switching power supply which concerns on Embodiment 1 of this invention. It is a block diagram which shows the structure of the switching power supply device in Embodiment 2 of this invention. It is a block diagram which shows the structure of the switching power supply device in Embodiment 3 of this invention. It is a block diagram which shows the structure of the power converter device for vehicles in Embodiment 4 of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same number in each figure shall show the same structure. Moreover, the arrow in each figure shall represent the direction through which a signal flows.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing a configuration of a switching power supply device 1 according to Embodiment 1 of the present invention. The primary side corresponding to the input side of the switching power supply device 1 is connected to the DC power source 2, and the secondary side corresponding to the output side is connected to the load circuit 3.

  Here, as the DC power source 2, for example, a lead battery, a lithium ion battery, or an electric double layer capacitor can be considered.

  Further, in the load circuit 3, an integrated circuit including a communication circuit 8a that communicates with another device (not shown) and a microcomputer or an ASIC that obtains communication contents and performs operations to perform various controls. A circuit 9 is provided.

  In the switching power supply device 1, a voltage conversion unit 4 that converts power supplied from the DC power supply 2 to a desired voltage is provided between the DC power supply 2 and the load circuit 3. In addition, the switching power supply device 1 includes a voltage control unit 6 that calculates an on time or an off time of the semiconductor switching element 5 included in the voltage conversion unit 4, and a frequency spreading control unit 7 that controls the switching frequency of the semiconductor switching element 5. It has.

  FIG. 2 is a diagram illustrating a specific configuration example of the voltage conversion unit 4 in the switching power supply device 1 according to Embodiment 1 of the present invention. As a specific configuration of the voltage conversion unit 4, for example, as shown in FIG. 2A, a so-called general configuration in which a smoothing circuit including a semiconductor switching element 5 and a reflux element 10 and a coil 11 and a capacitor 12 is configured. A known step-down circuit configuration is conceivable. Here, the reflux element 10 may be a semiconductor switching element 5 in addition to a diode. As the semiconductor switching element 5, for example, a MOSFET can be considered.

  In addition, the voltage conversion unit 4 includes a current sensor 13 in the vicinity of the coil 11 that makes the direction of current from the DC power supply 2 to the load circuit 3 positive. As the current sensor 13, for example, a non-contact type sensor using a Hall element is conceivable. Alternatively, the current sensor 13 may be a current detection circuit using a differential amplifier in which a shunt resistor is provided in the current path and the voltage across the shunt resistor is a differential input.

  As another configuration of the voltage conversion unit 4, for example, as shown in FIG. 2B, a step-up configuration in which the assembly of each element is changed, or as shown in FIG. A buck-boost configuration combining FIG. 2 (b) is also conceivable.

  As the voltage control unit 6, for example, a desired voltage output from the voltage conversion unit 4 is fed back as an input voltage, and a deviation between the desired voltage and the input voltage is used as a control amount to turn on the semiconductor switching element 5 within the switching frequency. A so-called generally known pulse width modulation circuit (PWM control circuit) and a gate drive circuit that calculate a time or an off time and output a gate drive signal that is a control signal of the semiconductor switching element 5 can be considered.

  FIG. 3 is a diagram illustrating an example of a triangular wave generation circuit of the voltage control unit 6 in the switching power supply device 1 according to Embodiment 1 of the present invention. In the first embodiment, the triangular wave generation circuit corresponding to the pulse width modulation circuit has a configuration capable of spreading the switching frequency as shown in FIG. 3, for example.

  In FIG. 3, a pulse generator 14 using an analog or digital timer circuit (not shown) outputs a pulse train. The output pulse is input to the counter circuit 15 and counted up, and a triangular wave matching the switching frequency is output via the DA converter 16.

  Here, as frequency spreading, a method of changing the timer time in the timer circuit in the pulse generator 14 continuously or discretely can be considered. Further, as a restriction on the frequency fluctuation range when performing frequency spreading, the spread frequency (variation width) is smaller than the switching frequency and is larger than the resolution bandwidth (for example, 10 kHz) at the time of radiation noise measurement. Must be big.

  The frequency spread control unit 7 receives the state of the load circuit 3 or the DC power supply 2 as an input and determines whether or not the frequency spread control is necessary. FIG. 4 is a diagram illustrating an example of the frequency spread control unit 7 in the switching power supply device 1 according to Embodiment 1 of the present invention. As a configuration of the frequency spread control unit 7, for example, as shown in FIG. 4, a method using a comparator 17a and an analog timer circuit 18 is conceivable.

  FIG. 5 is a timing chart of the frequency spread control unit 7 in the switching power supply device 1 according to Embodiment 1 of the present invention. More specifically, it is a timing chart for explaining the operation of the frequency spread control unit 7 having the circuit configuration in FIG. Hereinafter, the circuit operation of FIG. 4 will be described with reference to the timing chart of FIG.

  At time T0 in FIG. 5, a constant voltage serving as a threshold is applied from the constant voltage source 19 to the positive input terminal of the comparator 17a. The voltage value of the capacitor in the analog timer circuit 18 is applied to the negative input terminal of the comparator 17a.

  Since there is no charge on the capacitor, the output of the comparator 17a is a Hi signal. At this time, the watchdog pulse signal is in the Lo signal state. During the period from time T0 to time T1, the capacitor is charged by the constant current source in the analog timer circuit 18, and the potential rises.

  At time T1, since the watchdog pulse signal changes to the Hi signal, the transistor 21 is turned on, and the charge of the capacitor in the analog timer circuit 18 is discharged. Accordingly, the negative input terminal of the comparator 17a has a voltage value in the state at time T0.

  At time T2, the watchdog pulse signal changes to the Lo signal again. As a result, the capacitor is charged by the constant current source in the analog timer circuit 18, and the voltage applied to the negative input terminal of the comparator 17a increases.

  If the watchdog pulse signal is not input within a predetermined time, the negative input voltage of the comparator 17a exceeds the positive input voltage as shown at time T3 in FIG. 5, and the comparator 17a Is output.

  As described above, when the watchdog pulse signal output from the load circuit 3 is input within a predetermined time, the load circuit 3 is in a predetermined operation state. Will remain.

  In such a state that the Hi signal is output from the frequency spread control unit 7, the voltage control unit 6 performs the frequency spread control so that the timer circuit in the pulse generator 14 shown in FIG. The timer time at is changed continuously or discretely. That is, the Hi signal output from the comparator 17a corresponds to a diffusion control permission signal, and the Lo signal corresponds to a diffusion control inhibition signal.

  On the other hand, when the watchdog pulse signal output from the load circuit 3 is not input within a predetermined time, the output of the comparator 17a changes to the Lo signal because the load circuit 3 is not in a predetermined operation state. To do. In this state where the Lo signal is output from the frequency spread control unit 7, the voltage control unit 6 prohibits the frequency spread control.

  As an example of the configuration of the frequency spread controller 7, a circuit configuration for monitoring the periodicity of the rising edge of the watchdog pulse signal is shown as an example in FIG. However, the present invention is not limited to such a circuit configuration. For example, it is conceivable to use a window-type monitoring circuit that determines the periodicity of the rising edge and falling edge of the watchdog pulse signal. By using such a monitoring circuit, the operation of the load circuit 3 is more preferably performed. The state can be determined.

  Alternatively, as a method for knowing the operation state of the load circuit 3 in more detail, it is conceivable to use an inquiry response system. FIG. 6 is a diagram illustrating another configuration example of the frequency spreading control unit 7 in the switching power supply device 1 according to Embodiment 1 of the present invention. The frequency spread control unit 7 illustrated in FIG. 6 includes a communication circuit 8b therein, and transmits an inquiry request to the communication circuit 8a in the load circuit 3 via the communication circuit 8b.

  On the other hand, in the load circuit 3, the integrated circuit 9 including the microcomputer or the ASIC receives the introduction request via the communication circuit 8a and outputs an inquiry response. If the inquiry response from the integrated circuit 9 is correct, the frequency spread control unit 7 performs frequency spread control.

  As described above, according to the first embodiment, when the periodicity of the watchdog pulse signal output from the microcomputer or ASIC in the load circuit or the inquiry response with the load circuit satisfies a predetermined requirement. Has a configuration in which it is determined that the load circuit is in a predetermined operating state and frequency spread control is performed. As a result, it is possible to prevent the power output from becoming unstable by performing frequency spreading at the time of a light load when the load circuit is not operating.

  Furthermore, frequency spreading control can be performed in a state where the consumption current of the load circuit is large. As a result, radiation noise can be suppressed and compatibility with radio wave compatibility can be achieved.

Embodiment 2. FIG.
In the second embodiment, in addition to the first embodiment, a method for determining whether or not it is necessary to perform the frequency spread control more appropriately by monitoring the state of the DC power supply will be described. In the second embodiment, the voltage converter 4 will be described with reference to the configuration shown in FIG.

  FIG. 7 is a block diagram showing the configuration of the switching power supply apparatus according to Embodiment 2 of the present invention. In addition to the configuration of the first embodiment, the frequency spread control unit 7 according to the second embodiment further includes a comparator 17b that receives the power supply voltage of the DC power supply 2 and the output voltage of the switching power supply device 1 as inputs. Yes.

  Then, if the power supply voltage from the DC power supply 2 is lower than the output voltage of the switching power supply device 1, the comparator 17 b can output the Lo signal and prohibit the frequency spread control.

  As described above, according to the second embodiment, the periodicity of the watchdog pulse signal output from the microcomputer or ASIC in the load circuit or the inquiry response with the load circuit satisfies a predetermined requirement. Has a configuration in which it is determined that the load circuit is in a predetermined operating state and frequency spread control is performed. As a result, it is possible to prevent the power output from becoming unstable by performing frequency spreading at the time of a light load when the load circuit is not operating.

  Furthermore, frequency spreading control can be performed in a state where the consumption current of the load circuit is large. As a result, radiation noise can be suppressed and compatibility with radio wave compatibility can be achieved.

  In addition, according to the second embodiment, the voltage supplied from the DC power supply is monitored, and when the switching power supply apparatus performs the boosting operation, it is determined that the DC power supply is not in a predetermined state, and the frequency spread control It has a configuration that prohibits As a result, it is possible to realize a further effect that power can be stably supplied to the load circuit even during the step-up operation with poor power conversion efficiency and a small power supply capacity.

Embodiment 3 FIG.
In the present third embodiment, a method for more simply monitoring the state of the load circuit 3 and determining whether or not to implement the frequency spread control will be described as compared with the configuration of the second embodiment.

  FIG. 8 is a block diagram showing a configuration of the switching power supply apparatus according to Embodiment 3 of the present invention. That is, the configuration of FIG. 8 in the third embodiment has a current sensor 13 and a comparator 17c instead of the comparator 17b as compared with the configuration of FIG. 7 in the previous second embodiment. The input signals connected to 17c are different.

  The current sensor 13 detects a current flowing through the coil 11 in the voltage conversion unit 4. If the current flowing through the coil 11 is greater than 0 and a positive value, the comparator 17c outputs a Hi signal and performs frequency spread control. Conversely, if the current flowing through the coil 11 is 0 or a negative value, the comparator 17c outputs a Lo signal and prohibits frequency spread control.

  As described above, according to the third embodiment, when the current flowing through the coil in the voltage converter is always larger than 0, that is, when the switching power supply device is operating in the continuous mode, the load circuit is predetermined. It is determined that the operating state is, and a configuration for performing frequency spread control is provided. As a result, it is possible to prevent the power output from becoming unstable by performing the frequency spread control at a light load when the load circuit is not operating.

  Furthermore, frequency spreading can be performed in a state where the consumption current of the load circuit is large. As a result, radiation noise can be suppressed and compatibility with radio wave compatibility can be achieved.

Embodiment 4 FIG.
In the fourth embodiment, a specific example in which the switching power supply according to the present invention described in the first to third embodiments is applied to a power conversion device will be described.

  FIG. 9 is a block diagram showing a configuration of a vehicle power conversion device according to Embodiment 4 of the present invention. In addition, although this Embodiment 4 demonstrates as an example the power converter device for vehicles, the power converter device used as the application object of the switching power supply device which concerns on this invention is not limited to vehicles.

  The power conversion apparatus 100 includes a three-phase bridge circuit 60 and a bridge control unit 70. The three-phase bridge circuit 60 is configured by connecting three phase bridge circuits (series bodies) in which two MOSFETs which are power semiconductor switching elements are connected in series, in parallel. The gate of each MOSFET is driven and controlled by the bridge controller 70.

  The MOSFETs 61a, 61b, 61c above the connection point between the MOSFETs of each phase bridge circuit constitute an upper arm, and the lower MOSFETs 61b, 62b, 63b constitute a lower arm.

  Note that a single-phase bridge circuit may be configured by connecting two serial bodies in which MOSFETs are connected in series in parallel. Further, the bridge circuit determines the parallel number of the phase bridge circuit according to the number of phases of the AC rotating electric machine 20, and may be other phase bridge circuits such as two phases and six phases in addition to the three phases.

  The DC terminal P on the high potential side, which is one terminal of the bridge circuit 60, is connected to the high potential side terminal of the DC power supply 2 (battery) that can be charged and discharged via the electrical wiring 110. Further, the low potential side DC terminal N which is the other terminal of the bridge circuit 60 is connected to the low potential side terminal of the DC power source 2 via the vehicle body ground and electrical wiring (both not shown).

  Further, the three-phase output terminals of the bridge circuit 60, that is, the connection points U, V, and W of the series body in which two MOSFETs are connected in series are respectively between the windings of the three armature windings of the AC rotating electric machine 20. Are connected individually.

  Note that various methods that have been proposed and realized in the past can be applied to the operation method of the AC rotating electrical machine 20, the specific AC-DC power conversion method of the power converter 100, or the DC-AC power conversion method. . Therefore, detailed description thereof is omitted here.

  The switching power supply device 1 according to the present invention described in the first to third embodiments is provided in the bridge control unit 70. The load circuit 3 includes a bridge control circuit using the pre-driver IC 30, a communication circuit 8a, and an integrated circuit 9 including a microcomputer or ASIC that performs desired power conversion.

  As in the first and third embodiments, the switching power supply 1 is based on the detection result of the watchdog pulse signal output from the microcomputer or the ASIC or the current flowing through the coil in the voltage converter 4. The state of the load circuit 3 is determined. Then, the switching power supply device 1 performs frequency spread control in a state where the consumption current of the load circuit 3 is large. As a result, radiation noise can be suppressed and compatibility with radio wave compatibility can be achieved.

  Similarly to the second embodiment, the voltage supplied from the DC power supply 2 is monitored, and when the switching power supply device 1 performs the boosting operation, it is determined that the DC power supply 2 is not in a predetermined state. When the switching power supply device 1 determines that the DC power supply 2 is not in a predetermined state, the switching power supply device 1 prohibits the frequency spread control. As a result, even if a transient voltage drop of the DC power supply 2 occurs due to starter driving at the time of starting the engine, the frequency spread control can be prohibited and power supply to the load circuit 3 can be executed stably.

  DESCRIPTION OF SYMBOLS 1 Switching power supply device, 2 DC power supply, 3 Load circuit, 4 Voltage conversion part, 5 Semiconductor switching element, 6 Voltage control part, 7 Frequency spreading | diffusion control part, 8a, 8b Communication circuit, 9 Integrated circuit, 10 Reflux element or rectifier 11 coil, 12 capacitor, 13 current sensor, 14 pulse generator, 15 counter circuit, 16 DA converter, 17a, 17b, 17c comparator, 18 analog timer circuit, 19 constant voltage source, 20 AC rotating electrical machine, 21 transistor, 30 pre Driver IC, 50 Internal power supply voltage, 60 Bridge circuit, 61a, 61b, 62a, 62b, 63a, 63b Power semiconductor switching element, 70 Bridge control unit, 100 Power converter, 110 Electrical wiring.

Claims (6)

A switching power supply that generates a desired output voltage by performing voltage conversion on a power supply voltage from a DC power supply, and supplies the desired output voltage to a load circuit connected downstream,
A semiconductor switching element, a coil and a capacitor for stabilizing a voltage, and the semiconductor switching element is controlled to be turned on / off according to a control signal, thereby performing a step-down operation or a step-up operation as the voltage conversion, A voltage converter that generates a desired output voltage and supplies power to the load circuit;
On-time or off-time of the semiconductor switching element within a switching frequency is calculated based on at least one information of the power supply voltage from the DC power supply, the output voltage of the voltage converter, or the current flowing through the coil. A voltage control unit that outputs the control signal for on / off control of the semiconductor switching element;
A frequency spreading control unit that determines whether or not to perform spreading control of switching frequency based on a monitoring result of the state of the load circuit or the DC power supply, and outputs a spreading control permission signal or a spreading control prohibition signal;
When the voltage control unit receives the spreading control permission signal from the frequency spreading control unit, the voltage control unit executes spreading control of the switching frequency and outputs the control signal generated based on the switching frequency subjected to spreading control. Switching power supply. The spread spectrum control unit outputs the spread control permission signal when the watchdog pulse signal output from the load circuit is output in a predetermined cycle, and in the other cases, the spread control permission signal is output. The switching power supply device according to claim 1, which outputs a control inhibition signal. The frequency spread control unit outputs the spread control permission signal when receiving the inquiry response signal from the load circuit as a response to the inquiry request signal output to the load circuit, and otherwise The switching power supply according to claim 1, wherein the diffusion control inhibition signal is output. The frequency spread control unit outputs the spread control prohibition signal when the power supply voltage of the DC power supply is equal to or lower than the output voltage of the voltage conversion unit, and otherwise outputs the spread control permission signal. The switching power supply device according to claim 2 or 3. The frequency spread control unit monitors the state of the load circuit by reading the current value flowing through the coil in the voltage conversion unit, defines the direction of flow from the DC power source to the load circuit as positive, and the current value 2. The switching power supply according to claim 1, wherein the spreading control permission signal is output in a continuous mode that always takes a positive value larger than 0, and the spreading control inhibition signal is output in other cases. apparatus. A plurality of phase bridge circuits having upper and lower arms connected in series by connecting power semiconductor switching elements are connected in parallel, and both ends of the phase bridge circuit are connected to a chargeable / dischargeable DC power source, and the upper and lower arms of the phase bridge circuit A bridge circuit in which a connection point between the power semiconductor switching elements is connected to an AC terminal of an armature winding of a multiphase rotating electrical machine;
A bridge control unit that performs AC-DC power conversion control or DC-AC power conversion control by switching control of the bridge circuit,
The bridge circuit uses the switching power supply device according to any one of claims 1 to 5, and determines whether or not to perform switching frequency diffusion control, and executes switching control of the power semiconductor switching element. Power conversion device.

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