TWI550984B - Power supply - Google Patents

Description

Power supply unit

The present invention relates to a power supply device that generates a DC power source from an AC power source.

Most of the components that make up electrical machinery operate on the basis of DC power. Therefore, the electric machine has a power supply circuit or an AC adapter for generating a DC power source from an AC power source supplied from a commercial power source or the like. This current circuit typically contains a power component with a switching element. Since the power element is a semiconductor element that flows a large amount of current, the junction temperature of the semiconductor element tends to be high. Power components can be destroyed or accelerated when the junction temperature is above a predetermined temperature range. Therefore, when utilizing a power component, it is necessary to make the junction temperature not exceed a predetermined temperature range. Here, Patent Documents 1 to 4 disclose techniques for controlling the junction temperature of a power element or the current flowing through a power element.

Patent Document 1 discloses a technique of reading a corresponding limited current based on a fluctuation signal of a peripheral temperature. Patent Document 2 discloses a technique in which a thermistor is mounted in a semiconductor and the temperature of the semiconductor device is detected through the thermistor. Patent Document 3 discloses a technique for performing diagnosis and stability monitoring of power electronic components based on both instantaneous measured values and measured value trends (including, for example, voltage, current, and temperature change rates of the system). Patent Document 4 discloses an example of a current setting value for operating a semiconductor device in an Area of Safety Operation (ASO).

[Patent Document 1] Japanese Special Kaiping 07-039062

[Patent Document 2] Japanese Patent Laid-Open No. 07-074306

[Patent Document 3] Japanese Special Table 2006-508627

[Patent Document 4] Japanese Special Opening 2001-078130

However, in the techniques disclosed in Patent Documents 1 to 4, there is a problem that the semiconductor element has to be disposed in a mechanism for directly monitoring the junction temperature of the semiconductor element, and the selection of the semiconductor device including the semiconductor element is limited.

An aspect of a power supply device according to the present invention includes a power supply control unit that outputs a Pulse Width Modulation (PWM) signal having a duty ratio that is dependent on a voltage of a DC system power supply. a difference between the target voltages; a power circuit having a switching element mounted with a heat sink, the power circuit switching the switching element based on the PWM signal, and a first temperature sensor mounted on the heat sink The externally supplied AC power output is the DC system power supply, wherein the power control unit is configured to change the rate of change of the temperature information obtained by the first temperature sensor to be greater than a protection start temperature change rate for a duration exceeding a preset protection When the time threshold is started, the protection mechanism of the power circuit is operated, and the value of the protection start temperature change rate is changed based on the peripheral temperature obtained by the system temperature sensor, and the system temperature sensor is included The temperature inside the casing of the power circuit is monitored.

According to the power supply device of the present invention, the semiconductor element does not require a mechanism for directly monitoring the junction temperature, and the selection of the semiconductor element can be broadened.

1‧‧‧Phone system

10‧‧‧Power supply unit

11‧‧‧Power circuit

12‧‧‧Power Control Department

13‧‧‧Insulated circuit

20‧‧‧ telephone exchange

21‧‧‧System Control Department

22‧‧‧ memory

23‧‧‧ Instant Time Generation Department

24‧‧‧Interface circuit

31‧‧‧Rectifying and smoothing circuit

32‧‧‧Drive circuit

41‧‧‧AD conversion circuit

42‧‧‧ Computing Department

43‧‧‧PWM timer

44‧‧‧ memory

51‧‧‧Power components

52‧‧‧Semiconductor wafer

53‧‧‧Frame

54‧‧‧Solid substrate

55‧‧‧ Heat sink

56‧‧‧temperature sensor

HTSEN1‧‧‧First temperature sensor

HTSEN2‧‧‧Second temperature sensor

Tr‧‧‧ drive transistor

D‧‧‧ diode

L‧‧‧Inductors

C‧‧‧ capacitor

OVS‧‧‧ voltage observation point

OCS‧‧‧ current observation point

TM1, TM2‧‧‧ telephone terminal

Fig. 1 is a block diagram showing a telephone system relating to Embodiment 1.

Fig. 2 is a block diagram showing a power supply device of the first embodiment.

Fig. 3 is a view showing the arrangement of the power element, the heat sink, and the temperature sensor of the first embodiment.

Fig. 4 is a graph showing the relationship between the junction temperature and the temperature of the fins in the state in which the junction temperature increase rate is small in the power supply device of the first embodiment.

Fig. 5 is a graph showing the relationship between the junction temperature and the temperature of the fins in the state in which the junction temperature increase rate is large in the power supply device of the first embodiment.

Fig. 6 is a graph showing changes in the fin temperature in a state where the rated current is output as a load current in the power supply device of the first embodiment.

Fig. 7 is a view showing an example of table information in which temperature information is described in the power supply device of the first embodiment.

Fig. 8 is a schematic view showing a control method of the overcurrent protection setting value in the power supply device of the second embodiment.

Fig. 9 is a flow chart showing a control method of the overcurrent protection setting value in the power supply device of the second embodiment.

Fig. 10 is a schematic view showing a control method of the overcurrent protection setting value in the power supply device of the third embodiment.

Fig. 11 is a flow chart showing a control method of the overcurrent protection setting value in the power supply device of the third embodiment.

Example 1

Embodiments of the present invention are described below with reference to the drawings. The present invention relates to a power supply device. The power supply unit can be applied to a system other than the telephone system, and the system that can be used is not limited to the telephone system.

A block diagram of the telephone system 1 relating to Embodiment 1 is shown in Fig. 1. As shown in Fig. 1, the telephone system 1 of the first embodiment includes a power supply unit 10, a telephone exchange 20, telephone terminals TM1 and TM2, and a system temperature sensor SEN. The system temperature sensor SEN outputs temperature information TSEN indicating the temperature inside the casing (hereinafter referred to as ambient temperature) in the telephone system 1.

The power supply device 10 converts the AC power supplied from the external commercial system power supply into a DC system power supply. In the following description, the voltage of the DC system power supply is expressed as the DC output voltage VOUT. The power supply device 10 has a power supply circuit 11, a power supply control unit 12, and an insulating circuit 13.

The power supply circuit 11 includes a switching element on which a heat sink is mounted, and the switching element is switched based on a PWM signal generated by the power supply control unit 12, and the AC power supplied from the outside is output as a DC system power supply. The power control unit 12 outputs a PWM signal having a duty ratio corresponding to a difference between a voltage (DC output voltage VOUT) of the DC system power supply and a preset target voltage. Further, the power source control unit 12 is configured to cause the rate of change of the temperature information obtained from the first temperature sensor mounted on the heat sink to be greater than a preset protection start time threshold value when the duration of the protection start temperature change rate is greater than a preset protection start time threshold value. The protection mechanism of the power circuit 11 operates. The power supply control unit 12 can employ, for example, a micro processor unit (MPU) that performs various calculations and controls in accordance with a program. The insulating circuit 13 insulates the voltage observation point OVS and the current observation point OCS of the power supply circuit 11 from the input terminal of the power supply control unit 12, and outputs a signal having a signal level corresponding to the voltage obtained from each observation point. It is particularly effective to provide the insulating circuit 13 when the voltage observed at each observation point is larger than the input voltage range of the power supply control unit 12. In addition, the power supply device 10 will be described in detail later.

The telephone exchange 20 performs connection control between the telephone terminals TM1, TM2 and the station line. Telephone switch 20 operates based on DC system power. The telephone exchange 20 includes a system control unit 21, a memory 22, an instant clock generation unit 23, and a interface circuit 24.

The system control unit 21 performs connection control between the telephone terminal TM1 and the station line. The system control unit 21 can employ, for example, an MPU that performs various calculations and controls in accordance with the program. The memory 22 stores a program necessary for the operation of the system control unit 21. The capacity of this memory 22 is larger than the memory provided in the power supply unit 10. The instantaneous clock generation unit 23 generates a real time clock signal given to the system control unit 21. This real time clock signal is used to measure the time in the system control unit 21.

For example, the telephone terminals TM1 and TM2 are fixed telephones. The telephone terminals TM1, TM2 are connected to the interface circuit 24 of the telephone exchange 20. The telephone terminals TM1 and TM2 include a display unit (for example, a liquid crystal display (LCD)) that displays various information such as incoming call information, and a terminal control unit. The terminal control unit uses an MPU that performs various calculations and controls, for example, in response to a program.

Next, details regarding the power supply device 10 will be described. A detailed block diagram of the power supply unit 10 of the first embodiment is shown in FIG. As shown in FIG. 2, the power supply circuit 11 of the power supply device 10 of the second embodiment uses a power improvement circuit (Power Factor Correction circuit, PFC circuit) as a circuit for generating the DC output voltage VOUT. The power supply circuit 11 has a rectifying and smoothing circuit 31, a driving circuit 32, a switching element (for example, a driving transistor Tr), an inductor L, a diode D, a capacitor C, a heat sink temperature sensor HTSEN1, an HTSEN2, and a current sensing resistor Rs1. And resistors R1, R2. Further, the driving transistor Tr and the diode D are power elements through which a large current flows through the semiconductor substrate.

The rectifying and smoothing circuit 31 rectifies the AC input voltage supplied from the AC power source to output a DC voltage. This DC voltage is output to a power supply node connected to the positive output terminal of the rectifying and smoothing circuit 31 and a ground node connected to the negative output terminal.

The power supply node is inserted in series with the inductor L and the diode D. And a driving transistor Tr is connected between the node between the inductor L and the diode D and the ground node. The driving signal from the driving circuit 32 is given to the gate of the driving transistor Tr. The drive circuit 32 generates a drive signal based on the PWM signal output from the PWM timer 43 of the power supply control unit 12. Further, in the power supply circuit 11, the driving transistor Tr and the diode D are provided with fins. And a heat sink disposed on the driving transistor Tr, and a first temperature sensor (for example, a heat sink temperature sensor HTSEN1) for detecting the temperature of the heat sink is provided. A heat sink disposed on the diode D is provided with a second temperature sensor (for example, a heat sink temperature sensor HTSEN2) for detecting the temperature of the heat sink. Further, the temperature information detected by the fin temperature sensors HTSEN1 and HTSEN2 is the AD converter circuit 41 supplied to the power source control unit 12.

The capacitor C is disposed between the terminal on the output side of the power supply circuit 11 and the ground node in the terminal of the diode D. This capacitor C smoothes the pulse signal generated by the switching of the inductor L and the driving transistor Tr.

Further, resistors R1 and R2 are connected in series between the power supply node and the ground node. The node to which the resistor R1 and the resistor R2 are connected becomes the voltage observation point OVS. Further, a ground detecting node is inserted with a current detecting resistor Rs1. Further, the terminal of the current detecting resistor Rs1 on the side of the rectifying and smoothing circuit 31 becomes the current observation point OCS.

The power supply control unit 12 includes an AD conversion circuit 41, a calculation unit 42, a PWM timer 43, and a memory 44.

The AD conversion circuit 41 outputs a digital value corresponding to the voltage value of the current observation point OCS obtained by the transmission of the insulating circuit 13 and the voltage value of the voltage observation point OVS. Further, the power supply device 10 outputs a digital value corresponding to the AC input voltage value indicating the voltage level of the AC input voltage given by the AC power source. The output of the AD conversion circuit 41 corresponds to the system temperature sensor SEN, the heat sink temperature sensor HTSEN1, and the dispersion. The digital value of the temperature information output by the hot film temperature sensor HTSEN2. In addition, in Fig. 2, the temperature information output by the system temperature sensor SEN is represented as TSEN.

The calculation unit 42 updates the set value of the PWM timer 43 so that the difference between the DC output voltage VOUT generated as the DC system power supply and the preset target voltage value approaches zero. Further, the calculation unit 42 calculates the rate of change of the temperature information from the fin temperature sensors HTSEN1 and HTSEN2, and determines whether or not the current value flowing through the driving transistor Tr or the diode D is larger than the rated current value based on the rate of change of the temperature information. Further, the computing unit 42 issues a warning signal when it is determined that the current value flowing through the driving transistor Tr or the diode D is greater than the rated current value. The calculation unit 42 refers to the table information stored in the memory 44 to determine the relationship between the rate of change of the temperature information and the rated current. And through the warning signal, the operation of the power circuit 11 is stopped. The function of stopping the power supply circuit 11 is one of the protection mechanisms, and the protection mechanism varies depending on the design of the power supply circuit 11.

The PWM timer 43 outputs a PWM signal in accordance with the duty ratio of the set value given by the calculation unit 42. Further, the PWM timer 43 stops the generation of the PWM signal in response to the warning signal from the calculation unit 42. The memory 44 stores a program for determining the operation of the computing unit 42. Further, the memory 44 stores various pieces of information such as the table information used by the calculation unit 42 and the intermediate data generated by the calculation unit 42 during the calculation.

Next, the positional relationship between the power element, the heat sink, and the temperature sensor used in the power supply device 10 of the first embodiment will be described. Here, FIG. 3 is a view for explaining the arrangement of the power elements, the heat sinks, and the temperature sensors used in the power supply device 10 of the first embodiment.

As shown in FIG. 3, in the power supply device 10, individual components are used as the power elements 51 (for example, the driving transistor Tr and the diode D). The power element 51 is composed of a semiconductor wafer 52 having a structure that functions as a driving transistor Tr or a diode D, a frame 53, and a molding material that coats the semiconductor wafer 52. The power element 51 is then attached to the mounting plate 54 by a conductive material such as solder.

The heat sink 55 is attached to the back surface of the power element 51 (the surface on which the frame is exposed or the side of the frame 53 directly below the molding material). The heat sink 55 and the power element 51 are joined by a structural member such as a screw and a conductive paste. And the temperature sensor 56 is mounted to the heat sink 55.

As shown in FIG. 3, when the power component mounting method of the power supply device 10 is used, the temperature measured by the temperature sensor 56 will be different from the junction temperature of the semiconductor wafer 52. More specifically, the relationship between the temperature measured by the temperature sensor 56 and the junction temperature is: the false design temperature is T, the junction temperature of the power component and the thermal resistance of the package are Rjp [° C / W], packaging and heat dissipation. The thermal resistance of the contact portion between the sheets is Rph [° C / W], the thermal resistance of the heat sink is Rh [° C / W], and the thermal resistance of the contact portion between the heat sink and the temperature sensor is Rhs [° C / W], The thermal resistance of the package of the temperature sensor and the internal inductor is Rcs [° C / W], and the junction surface heat is Wj [W], which has the relationship expressed by the following mathematical formula 1.

[Math 1] T=(Rjp+Rph+Rh+Rhs+Rcs)×Wj

As shown in the above mathematical formula 1, the temperature measured by the temperature sensor 56 is different from the actual junction temperature. Further, since the heat sink is often radiated, when the rate of increase in the junction temperature is large, the rate of increase of the temperature measured by the temperature sensor 56 tends to be smaller than the rate of increase in the junction temperature, and the change in junction temperature is explained here. The relationship between the temperatures measured by the temperature sensor.

4 and 5 are views showing the relationship between the junction temperature increase rate and the temperature increase rate of the fins in the power supply device of the first embodiment. The temperature rise rate of the joint surface shown in Fig. 4 is smaller than that of Fig. 5.

As shown in Fig. 4, when the rate of rise of the junction temperature is small, the temperature of the radiator reaches the heating protection start temperature before the junction temperature reaches the maximum allowable junction temperature. Therefore, when the junction temperature increase rate is as shown in Fig. 4, the power supply device 10 can appropriately manage the junction temperature of the power element only by the temperature of the heat sink.

On the other hand, as shown in Fig. 5, when the junction temperature increase rate is large, the junction temperature reaches the maximum allowable junction temperature before the heat sink temperature reaches the heating protection start temperature. Therefore, when the junction temperature increase rate is as shown in Fig. 5, the power supply device 10 cannot appropriately manage the junction temperature of the power element only by the temperature of the heat sink.

Here, in the power supply device 10 of the first embodiment, based on the temperature information change rate obtained from the temperature sensors HTSEN1 and HTSEN2 of the heat sink, an overcurrent state in which the junction temperature exceeds the maximum allowable junction temperature is estimated. And based on the presumed result, the power element of the self-protection power supply circuit 11 is operated without the protection mechanism of the heating damage. The temperature detection and heating protection operation of the power supply device 10 of the first embodiment will be described below.

In the power supply device 10 of the first embodiment, the computing unit 42 reads the table information from the memory 44, and refers to the table information to determine the power component estimated based on the rate of change of the temperature information from the heat sink temperature sensors HTSEN1 and HTSEN2. Whether the output current is greater than the rated current and whether the junction temperature is within the specified range. The information recorded in the form information is described in detail here.

In the table information, when the power component to be monitored flows through the rated current, information on the rate of change of the temperature information obtained from the fin temperature sensors HTSEN1 and HTSEN2 is displayed, and the ambient temperature and the AC input voltage at the time of measurement are also described. .

Here, FIG. 6 is a view showing a temperature change of the heat sink when the rated current is output as the load current in the power supply device of the first embodiment. As shown in Fig. 6, the temperature information obtained from the heat sink temperature sensor is such that when the power component flows through the rated current, the power supply control unit 12 arrives at the start of power. The protection start temperature of the heating protection of the source circuit 11 rises at a constant speed. In the power supply device 10 of the first embodiment, the rate information ΔT of the temperature information shown in FIG. 6 is detected in advance with each ambient temperature and the AC input voltage to form table information. Further, the calculation unit 42 uses the rate of change ΔT of the temperature information described in the table information as the protection start temperature change rate. This form information is stored in the memory 44 of the power source control unit 12. The memory 44 is preferably a non-volatile memory.

Further, Fig. 7 is a view showing an example of table information in which the temperature information is described in the power supply device of the first embodiment. As shown in Fig. 7, the ambient temperature in the table information is defined as increments of 10 ° C, and the protection start temperature change rate ΔT when the AC input voltage is 80 V to 140 V for one ambient temperature is described.

In the power supply device 10 of the first embodiment, the calculation unit 42 determines the flow of the power component when the rate of change of the temperature information obtained from the heat sink temperature sensors HTSEN1 and HTSEN2 is larger than the protection start temperature change rate ΔT described in the table information. There is over current. Further, when the power element flows through the overcurrent state in which the overcurrent has continued to exceed the preset protection start time threshold value, the calculation unit 42 operates the protection mechanism that causes the power supply circuit 11 to be in a stopped state or the like. Through such processing, the arithmetic unit 42 operates the protection mechanism of the power supply circuit 11 before the temperature information obtained from the heat sink temperature sensors HTSEN1 and HTSEN2 reaches the protection start temperature when the overcurrent state occurs.

Further, when determining the overcurrent state, the calculation unit 42 determines the ambient temperature based on the temperature information obtained from the system temperature sensor SEN, and refers to the table information closest to the ambient temperature. When the overcurrent state is determined, the calculation unit 42 refers to the AC input voltage, and determines the heat sink temperature change rate ΔT as the criterion for determination in accordance with the AC input voltage closest to the obtained AC input voltage.

With the foregoing description, with respect to the power supply device 10 of the first embodiment, the temperature information change rate obtained from the heat sink temperature sensors HTSEN1, HTSEN2 is used to estimate whether the power component is in an overcurrent. status. Further, when the overcurrent state of the power element continues to exceed the preset protection start time threshold, the power supply device 10 determines that the junction temperature reaches the protection start temperature to operate the protection mechanism of the protection power supply circuit 11.

Thereby, in the power supply device 10 of the first embodiment, the power element can be in the rated range based on the rate of change of the junction temperature of the power element being small and the heat sink temperature different from the actual junction temperature. Internal operation.

Further, in the power supply device 10 of the first embodiment, since the junction temperature of the power element can be managed based on the temperature of the heat radiating fin of the auxiliary power element, the power element itself may not have a temperature sensor. Therefore, the selection range of the power elements used in the power supply device 10 of Embodiment 1 can be expanded.

Further, in the power supply device 10 of the first embodiment, since the junction temperature of the power element can be managed by the temperature of the heat sink, in the existing system including the power element having no temperature sensor, only the additional heat sink may be added. The temperature sensor and the control program installed in the power source control unit 12 are updated to improve the reliability of the system.

Further, in the power supply device 10 of the first embodiment, the junction temperature of the power element is managed by the power supply control unit 12 that performs the feedback control for maintaining the output voltage at the target voltage, so that the junction temperature for managing the power element can be reduced. And the newly added circuit. In other words, the power supply device 10 of the first embodiment can reduce the cost of designing and inspecting a circuit or the like for managing the junction temperature.

Example 2

In the second embodiment, another type of control regarding the power supply device 10 in the first embodiment will be described. In the second embodiment, the power supply control unit 12 causes the self-protection start temperature change rate when the output current value determined from the rate of change of the temperature information is greater than the preset overcurrent state for a duration exceeding the preset overcurrent allowable time. The calculated overcurrent protection start setting value falls below the initial value. Further, the power supply control unit 12 continues the range in which the output current state determined from the rate of change of the temperature information is determined to be the rated current state. When the period exceeds the preset restoring allowable time, the reduced overcurrent protection start setting value is restored to the initial value. In the power supply control unit 12 of the second embodiment, the control for changing the above-described overcurrent protection start setting value in accordance with the operating state of the power supply circuit 11 will be described below.

Here, the overcurrent protection start setting value is used to determine the current value estimated from the protection start temperature change rate ΔT and the protection start time threshold described in the first embodiment as the set value of the overcurrent state. For example, the current protection start set value can be defined by the product of the heat sink temperature change rate and the protection start time threshold.

Further, in the power supply device 10 of the second embodiment, the temperature information change rate obtained from the heat sink temperature sensors HTSEN1 and HTSEN2 is overcurrent with the duration of the change rate of the temperature information which is greater than the temperature change rate of the heat sink. The product of the allowable time derives the overcurrent state measurement value.

Further, in the power supply device 10 of the second embodiment, the overcurrent protection start setting value and the overcurrent state measurement value are compared, and when the overcurrent state measurement value is larger than the overcurrent protection start setting value, the protection mechanism of the protection power supply circuit 11 is operated. . Further, in the second embodiment, when the overcurrent protection start setting value is lowered, the protection start temperature change rate ΔT is lowered, but the overcurrent protection start setting value may be lowered because the protection start time threshold is lowered.

Next, a timing chart showing a control method for the overcurrent protection start setting value in the power supply device 10 of the second embodiment is shown in FIG. In the example shown in Fig. 8, the overcurrent protection start setting value is used as the initial value to activate the power supply device 10. The initial value of the overcurrent protection start setting value is set to a value larger than the protection start temperature change rate ΔT when the rated current flows through the ambient temperature and the AC voltage at this time point. Further, an overcurrent state of the power element occurs after the power supply device 10 is started, and the overcurrent state exceeds the overcurrent allowable time at the time point T1.

Therefore, the power supply device 10 reduces the value of the protection start temperature change rate ΔT which is based on the start of the time point T1, and lowers the overcurrent protection start setting value. Further, the protection start temperature change rate ΔT selected after the decrease is a value when the rated current flows through the ambient temperature and the AC input voltage at the time point.

Thereafter, at time T2, the current flowing through the power element is at a rated current state below the rated current exceeding the recovery allowable time. Accordingly, the power supply device 10 returns the overcurrent protection start setting value to the initial value. Further, after the time point T3, the power supply device 10 continues to operate based on the overcurrent protection start setting value set as the initial value.

Next, a timing chart showing the operation of the power supply device 10 of the second embodiment is shown in FIG. The operation of the power supply device 10 of the second embodiment will be described with reference to Fig. 9. As shown in FIG. 9, the power supply device 10 of the second embodiment controls the power supply circuit 11 by setting the overcurrent protection start setting value to the initial value at the time of startup (step S1). Thereafter, the power supply device 10 continues the normal operation while obtaining temperature information from the heat sink temperature sensors HTSEN1 and HTSEN2. Further, the power supply device 10 monitors whether or not an overcurrent has occurred in the power element based on the temperature information obtained from the heat sink temperature sensors HTSEN1 and HTSEN2 under normal operation (step S2).

Further, in the power supply device 10 of the second embodiment, if an overcurrent state is detected during normal operation (YES in step S2), the duration of the overcurrent state (for example, the elapsed time of the overcurrent state) is measured, and if the overcurrent is excessive The state elapsed time exceeds the overcurrent allowable time (YES in step S3), and the overcurrent protection start set value is lowered. Further, in the power supply device 10, the protection start temperature change rate is lowered to the initial value or lower, and the overcurrent protection start setting value is lowered. The reduced overcurrent protection start setting value is calculated from the ambient temperature at the time point and the heat sink temperature change rate when the rated current flows through the power element at the AC input voltage.

Thereafter, the power supply device 10 continues to operate if the overcurrent state setting value calculated from the heat sink temperature sensors HTSEN1 and HTSEN2 does not exceed the reduced overcurrent protection start setting value (steps S5 and S8). On the other hand, when the overcurrent state measured value exceeds the reduced overcurrent protection start set value, the power supply device 10 operates the protection mechanism of the protection power supply circuit 11 (steps S5 and S6).

Then, when the overcurrent state is released and the current flowing through the power element becomes the rated current state of the rated current or less, the elapsed time exceeds the restoration allowable time (YES in step S8), and the overcurrent protection start setting value is restored to the initial state. Value (step S9). Thereafter, the power supply device 10 continues the use state while continuing the processes of steps S2 to S9.

According to the above description, according to the power supply device 10 of the second embodiment, the overcurrent protection start setting value which is the threshold value for the protection function operation is set to be high in the initial state, and the overcurrent state continues to exceed the predetermined time (for example, the overcurrent is allowed). At the time), the overcurrent protection start setting value is lowered.

Two of the power components are specified here. The first system stipulates that even when a voltage and current higher than the rated voltage and the rated current are applied, the area of safety operation (ASO) can be safely used as long as it is below a certain time. ). The second system specifies the rated voltage and rated current of the maximum voltage and current that can be used regularly.

In this way, among the power elements, even if a voltage and a current equal to or higher than the rated voltage and the rated current are applied, the ASO can be safely used as long as the time for applying the voltages and currents is short. Therefore, in the power supply device 10 of the second embodiment, the power supply device 10 of the second embodiment transmits the initial value of the overcurrent protection start setting value based on the ASO, and sets the reduced overcurrent protection based on the rated voltage and the rated current. Starting the set value, it is possible to prevent the power supply device 10 from operating the protection mechanism in an instantaneous excessive current state.

For example, when the load connected to the power supply device 10 is a capacitive load, there is a possibility that an inrush current may occur at the time of startup. At this time, when the overcurrent protection start setting value is set based on the rated voltage and the rated current, and the overcurrent protection start setting value is fixed, the protection mechanism may be operated due to the inrush current at the startup, and the startup failure may occur. However, according to the power supply device 10 of the second embodiment, the initial value of the overcurrent protection start setting value is set to be high, and when the overcurrent state exceeds the overcurrent allowable time or more, the corresponding rated voltage and rated current are changed. Current protection starts the set value. As a result, the power supply device 10 of the second embodiment can realize a safe system that satisfies the specifications of ASO, rated voltage, and rated current while achieving stable operation for a capacitive load.

Example 3

In the third embodiment, a different mode of the method of changing the overcurrent protection start setting value described in the second embodiment will be described. In the third embodiment, when the power supply circuit 11 is activated, the power supply control unit 12 sets the overcurrent protection start setting value to the initial value and activates the power supply circuit, and based on the initial value between the self-starting and the preset startup elapsed time. The power supply circuit operates to set the overcurrent protection start setting value to a value lower than the initial value after the elapsed time has elapsed. Further, when the output current state determined by the rate of change of the temperature information is within the range determined to be the rated current state, the power supply control unit 12 restores the reduced overcurrent protection start setting value. To the initial value. The control in which the above-described overcurrent protection start setting value changes in accordance with the operating state of the power supply circuit 11 in the power supply control unit 12 of the third embodiment will be described below.

Here, in the third embodiment, parameters such as an overcurrent protection start set value, an overcurrent state elapsed time, a rated current state elapsed time, an overcurrent allowable time, and a recovery allowable period are also used. These parameters are the same as in the second embodiment. Therefore, the description thereof is omitted. On the other hand, in the third embodiment, the startup elapsed time is utilized as a new parameter. This startup elapsed time is elapsed from the start of the power supply circuit 11 For example, it is possible to comply with the time range of the utilization range specified by the ASO. The startup elapsed time is set to, for example, several tens of milliseconds or more and several tens of seconds or less.

Next, a timing chart showing a control method of the overcurrent protection start setting value in the power supply device 10 of the third embodiment is shown in FIG. In the example shown in Fig. 10, the overcurrent protection start set value is used as the initial value to activate the power supply device 10. The initial value of the overcurrent protection start setting value is set to a value at which the protection start temperature change rate ΔT when the rated current flows is higher than the ambient temperature and the AC input voltage at the time point. Then, the power supply device 10 lowers the overcurrent protection start setting value at the time point T11 at which the elapsed time has elapsed after the power supply device 10 is started.

Thereafter, at time T12, the current flowing through the power element becomes a rated current state below the rated current and exceeds the recovery allowable time. Accordingly, the power supply device 10 restores the overcurrent protection start setting value to the initial value. Further, after the time point T12, the power supply device 10 continues to operate based on the overcurrent protection start setting value set as the initial value.

Next, a timing chart showing the operation of the power supply device 10 of the third embodiment is shown in FIG. The operation of the power supply device 10 of the third embodiment will be described with reference to Fig. 11. As shown in Fig. 11, with respect to the power supply device 10 of the third embodiment, the overcurrent protection start setting value is set to an initial value at the time of startup, and the power supply circuit 11 is controlled with the initial value between the elapsed elapsed time (step S11). ).

Further, once the elapsed time has elapsed, the power supply device 10 of the third embodiment lowers the overcurrent protection start setting value (step S11). Further, in the power supply device 10, the overcurrent protection start setting value is lowered by lowering the protection start temperature change rate to be smaller than the initial value. The reduced overcurrent protection start setting value is calculated from the temperature around the time point and the AC input voltage, and the rate of change of the heat sink temperature when the rated current flows through the power element.

After that, the power supply device 10 continues to operate if the overcurrent state measured value calculated from the fin temperature sensors HTSEN1 and HTSEN2 does not exceed the reduced overcurrent protection start set value (steps S12 and S13). On the other hand, the power supply device 10 operates the protection mechanism for the power supply circuit 11 when the overcurrent state measurement value exceeds the reduced overcurrent protection start setting value (steps S12, S13).

When the power supply device 10 cancels the overcurrent state and the current flowing through the power element becomes the rated current state or less, the duration of the rated current state exceeds the restoration allowable time (YES in step S15), and the overcurrent protection start setting value is restored to Initial value (step S16)

After that, if the power supply device 10 does not detect the overcurrent state (NO in step S17), the power supply device 10 maintains the normal use state. On the other hand, when the power supply device 10 detects the overcurrent state (YES in step S17) and the overcurrent state exceeds the allowable overcurrent time (YES in step 18), the overcurrent protection start setting value is lowered (step S11). ). In other words, after the power supply device 10 of the third embodiment restores the overcurrent protection start setting value to the initial value in step 16, the processing of steps S11 to S18 is repeatedly performed to perform the power supply device 10 with respect to the second embodiment. The same operation.

According to the above description, in the power supply device 10 of the third embodiment, after the period in which the occurrence of the surge current at the time of startup due to the capacitive load is high, the overcurrent protection start setting value is forcibly lowered until The power supply circuit 11 operates in a range of rated voltage and rated current until the output state of the power supply circuit 11 is stabilized. By doing so, the reliability of the power supply device 10 system of the third embodiment can be improved to the power supply device 10 of the second embodiment.

In addition, the surge current generation time is between several tens of milliseconds and hundreds of milliseconds, and the time required for the power element to be destroyed by overcurrent and heating takes several tens of seconds. Therefore, the start time and the overcurrent allowable time are set to match the occurrence time of the surge current. Protect the start time threshold to The time range that does not exceed the damage due to overcurrent and heating is preferred. By setting each time in this way, it is possible to prevent malfunction of the power supply device 10.

Further, the present invention is not limited to the above-described embodiments, and may be appropriately modified within the scope not exceeding the gist of the present invention. For example, in the foregoing embodiment, although the information obtained from the heat sink temperature sensor is used to estimate the junction temperature, when the temperature sensor capable of directly monitoring the junction temperature of the power component of the control object is installed in the power component, The processing of the foregoing embodiment can also be performed based on the information of the temperature sensor. By using the temperature sensor built in the power element, it is possible to perform more precise junction temperature management than the power supply device 10 of the foregoing embodiment.

1‧‧‧Phone system

10‧‧‧Power supply unit

11‧‧‧Power circuit

12‧‧‧Power Control Department

13‧‧‧Insulated circuit

20‧‧‧ telephone exchange

21‧‧‧System Control Department

22‧‧‧ memory

23‧‧‧ Instant Time Generation Department

24‧‧‧Interface circuit

TM1, TM2‧‧‧ telephone terminal

Claims (5)

A power supply device includes: a power control unit that outputs a Pulse Width Modulation (PWM) signal having a duty ratio that is dependent on a voltage of a DC system power supply and a preset target voltage a power supply circuit having a switching element mounted with a heat sink and a first temperature sensor mounted on the heat sink, the power circuit switching the switching element based on the PWM signal, and the external power source is externally given The output is the DC system power supply, wherein the power control unit is configured to change the rate of change of the temperature information obtained by the first temperature sensor to be greater than a preset start time threshold of the protection start temperature change rate. While operating the protection mechanism of the power circuit, the value of the protection start temperature change rate is changed based on the peripheral temperature obtained by a system temperature sensor, and the system temperature sensor is for the machine including the power circuit The temperature inside the shell is monitored. The power supply device of claim 1, wherein the power control unit determines that the output current value from the rate of change of the temperature information is greater than a preset overcurrent state for a duration exceeding a preset allowable overcurrent time. When the overcurrent protection start setting value calculated from the protection start temperature change rate is lowered to be lower than the initial value, and the output current state determined from the rate of change of the temperature information is judged to be the rated current state When the duration of the range exceeds the preset recovery allowable time, the reduced overcurrent protection start set value is restored to the initial value. The power supply device of claim 1 or 2, wherein the power supply control unit, when the power supply circuit is activated, The overcurrent protection start setting value calculated from the protection start temperature change rate is set to an initial value to activate the power supply circuit, and the power supply circuit is operated based on the initial value between the startup and the preset startup elapsed time. After the elapsed time of the start, the overcurrent protection start setting value is set lower than the initial value, and the time when the output current state determined from the temperature information change rate is within the range determined to be the rated current state is continuously exceeded. When the preset restoration allowable time is reached, the reduced overcurrent protection start setting value is restored to the initial value. The power supply device of claim 1, wherein the power control unit has a form information indicating a relationship between an ambient temperature and an alternating voltage of the alternating current power source and a rate of change of the temperature information, the power control unit Refer to the table information to estimate the output current value flowing through the switching element. The power supply device of claim 1, wherein the power supply circuit comprises a diode, the diode is mounted with a heat sink and a second temperature sensor, and the second temperature sensor is configured to detect the heat sink. The temperature control unit makes the power circuit of the power supply circuit when the rate of change of the temperature information obtained from the second temperature sensor is greater than a preset protection start time threshold for a duration greater than the protection start temperature change rate. The protection agency operates.