JP4805197B2 - Variable voltage power supply - Google Patents

Description

  The present invention relates to a variable voltage power supply apparatus that can significantly change a DC voltage supplied to a load device.

  Various configurations have already been proposed and put into practical use for power supply devices that supply a DC voltage to a load device. For example, a switching power supply device that stabilizes a DC voltage supplied to a load device by switching control is generally configured to detect an output voltage and control a switching ON period corresponding to a difference from a set reference voltage. It is. In addition, a power supply device that performs charging / discharging using a battery as a load device has an output voltage that substantially corresponds to the voltage of the battery, detects the charging / discharging current, and has a configuration for controlling to a predetermined charging / discharging current. is there.

In addition, since the power supply device has a maximum current that can be supplied to the load device, a configuration with an overcurrent protection function that detects the load current and stops the supply before reaching the maximum current is also common. is there. Also known is a configuration in which the input voltage to the power supply can be changed. In this case, if the set value of overcurrent protection is constant, the internal power consumption is higher when the input voltage is higher than when the input voltage is low. Therefore, means for automatically reducing the set value of overcurrent protection has been proposed at high input voltages (see, for example, Patent Document 1).
JP 2004-343900 A

  The load device is generally configured so that the input voltage is constant. For example, when the load device is a test device that performs a motor characteristic test or the like, a predetermined device is used so that the motor of the device under test does not burn out. It has a current control function that supplies current, an overcurrent protection function, etc., and there are cases where the output characteristics are tested by changing the voltage applied to the motor, and the voltage applied to the DUT is changed. In this case, the voltage input from the power supply device to the load device is changed. Even when the voltage input from such a power supply device to the load device is changed, it is necessary to configure the current control function and the overcurrent protection function to operate, but the voltage input to the load device increases rapidly. In this case, a surge current flows due to a response delay of the current control function on the load device side. This surge current is detected by the overcurrent protection function, and there is a problem that the load device stops operating.

  For example, as shown in FIG. 4A, in the state where a load device 42 is connected to the power supply device 41 and a predetermined DC voltage is supplied to the load device 42, the output voltage of the power supply device 41 is changed. When it is rapidly increased, a surge current flows from the response delay of the current control function of the load device 42 as described above. In this case, assuming that the impedance between the load device 42 and the current supply line is 1Ω, a voltage of 10 V is output from the power supply device 41 and supplied to the load device 42 as shown in FIG. In the state in which the current is flowing, the load device 42 maintains the current at 10 A by the internal current control function, but when the output voltage of the power supply device 41 is suddenly increased from 10 V to 100 V, From the response delay of the current control function of the load device 42, a surge current of 100A flows. As a result, an overcurrent protection function or the like acts to stop the function of the load device 42. In order to avoid such a problem, it is conceivable to moderate the change in the voltage supplied to the load device 42. However, there is a problem that the time required for switching the voltage supplied to the load device 42 becomes long and the test contents of the response characteristics of the motor output in the above case are not sufficient.

  The present invention aims to solve the above-described conventional problems, and has a configuration in which a surge current does not flow in the load device even when voltage control is performed to rapidly change the voltage supplied from the power supply device to the load device. provide.

  The variable voltage power supply device of the present invention supplies a stabilized output voltage to the load device, and supplies the output voltage to the load device by switching control in the variable voltage power supply device capable of changing the output voltage. Stabilization control of the output voltage of the switching power supply unit and the output voltage of the switching power supply unit so as to be the output voltage corresponding to the voltage reference value by comparing the output voltage of the switching power supply unit with a changeable voltage reference value A voltage control unit for performing, a current value storage unit for detecting and storing a current supplied to the load device, and the switching when a detected current value for detecting a current supplied to the load device exceeds an overcurrent detection reference value The overcurrent protection is performed by dropping the output voltage of the power supply unit, and when the output voltage is changed by changing the voltage reference value, the overcurrent detection reference value is set in advance for a certain period. And a current control unit for controlling the switching power supply unit to change the current reference value in proportion to the stored detected current value to the current value storage unit in a constant current mode.

  Also, a start signal for changing the output voltage of the switching power supply unit is input to the voltage control unit, the current control unit, and the current value storage unit, and the current value storage unit uses the start signal as a trigger to A current value obtained by detecting a current supplied to the load; and the voltage control unit has a configuration for changing a voltage reference value to be compared with the output voltage using the start signal as a trigger, and the current control The unit detects the current to be supplied to the load device by switching the overcurrent detection reference value to a current reference value corresponding to the current value stored in the current value storage unit for a certain period using the start signal as a trigger. Compared with the detected current value, the switching power supply unit is controlled in a constant current mode.

  When the voltage reference value is changed so that the output voltage supplied from the switching power supply unit to the load device suddenly increases, the output voltage is controlled to increase, and the current supplied to the load device is controlled in a constant current mode for a certain period. Therefore, even if a sudden increase control of the output voltage supplied to the load device is performed without generating a surge current, the increased output voltage can be supplied to the load device to continue the operation.

  Referring to FIG. 1, the variable voltage power supply device of the present invention includes a switching power supply unit 1 that supplies an output voltage to the load device 8 by switching control, and an output voltage of the switching power supply unit 1 and a changeable voltage reference value. In comparison, the voltage controller 4 that controls the stabilization of the output voltage of the switching power supply unit 1 and the current that is detected and stored in the load device 8 so that the output voltage corresponds to the voltage reference value. When the detected current value for detecting the current supplied to the value storage unit 6 and the load device 8 exceeds the overcurrent detection reference value, the output voltage of the switching power supply unit 1 is dropped to perform overcurrent protection, and the voltage reference When changing the value and changing the output voltage, in a constant current mode, the overcurrent detection reference value is changed to a current reference value proportional to the detected current value stored in the current value storage unit 6 for a certain period of time. switch And a current control unit 5 for controlling the mode power supply unit 1.

  FIG. 1 is an explanatory diagram of Embodiment 1 of the present invention, where 1 is a switching power supply unit, 2 is a current detection unit, 3 is an output control unit, 4 is a voltage control unit, 5 is a current control unit, and 6 is a current value. A storage unit, 7 is a current reference value generation unit, and 8 is a load device. The switching power supply unit 1 includes a current detection unit 2 that detects a current supplied to the load device 8, and includes a switching element such as a transistor (not shown), a transformer, and a rectifying / smoothing circuit. . The load device 8 includes a current control function and an overcurrent protection function for controlling the current used by the load device 8 to be a set value based on the voltage supplied from the switching power supply unit 1 as described above. It has a configuration.

  The voltage control unit 4 compares the output voltage of the switching power supply unit 1 with a set voltage reference value, and controls the ON period of the switching power supply unit 1 via the output control unit 3 in accordance with the error. The switching power supply unit 1 is controlled by the voltage mode. Therefore, the output voltage applied from the switching power supply unit 1 to the load device 8 can be changed by changing the voltage reference value. Further, the current control unit 5 includes a current detection value obtained by detecting the current supplied to the load device 8 by the current detection unit 2, a current reference value from the current reference value generation unit 7, or an overcurrent detection value not shown. When the output voltage is not changed, the switching power supply unit 1 is controlled via the output control unit 3 when the current detection value exceeds the overcurrent detection reference value compared to the overcurrent detection reference value. Then, overcurrent protection is performed by dropping the output voltage.

  When changing the output voltage, the voltage reference value in the voltage control unit 4 is switched by the start signal. Thereby, the switching power supply unit 1 is controlled from the voltage control unit 4 via the output control unit 3 so that the output voltage is a value corresponding to the voltage reference value. Further, the start signal is input to the current control unit 5 and the current value storage unit 6, and the detected current value detected by the current detection unit 2 is stored in the current value storage unit 6 using the start signal as a trigger. The stored detected current value is input to the current control unit 5 as a current reference value by the current value reference value generation unit 7. The current control unit 5 uses the start signal as a trigger to switch from the overcurrent detection reference value to the current reference value from the current reference value generation unit 7 for a predetermined period of time. In comparison, the operation is performed in a constant current mode in which the current according to the current reference value is controlled to flow to the load device 8. That is, the output voltage is rapidly increased by operating for a certain period in the constant current mode in which the current at that time is stored by the start signal when the output voltage is changed, and the current is maintained and supplied to the load device 8 side. Even if it is made to occur, generation of surge current can be prevented.

  FIG. 2 is an operation explanatory diagram, showing an output voltage of the switching power supply unit 1, an output current, a start signal, and a current control period in which control is performed in a constant current mode for a certain period using the start signal as a trigger. When the output voltage of the switching power supply unit 1 is rapidly increased to a value indicated as the set voltage, the set voltage to be compared with the output voltage in the voltage control unit 4 is rapidly increased as shown in the figure, and the voltage control unit 4 and the current The start signal input to the control unit 5 and the current value storage unit 6 is used as a trigger to shift from the constant voltage mode to the constant current mode for a certain period, and when the start signal stored in the current value storage unit 6 is input or immediately before the start signal is input. On the basis of the detected current value, a current reference value is generated by the current reference value generation unit 7 and input to the current control unit 5. Thereby, the current control unit 5 controls the switching control unit 1 by the output control unit 3 so that the current detection value by the current detection unit 2 maintains the current reference value from the current reference value generation unit 7. The current control period in the constant current mode is set to a preset period. Thereafter, the current control period shifts to the normal constant voltage mode, and the changed output voltage is supplied to the load device 8. In this way, when the output voltage of the switching power supply unit 1 is rapidly increased, the generation of surge current can be prevented by performing output control in the constant current mode for a certain period.

  3 is an explanatory diagram of the main part of the first embodiment of the present invention, in which 11 is a switching output unit, 12 is a current detection resistor, 13 is an output control unit, 14 is a current display unit, 15 is a voltage display unit, Reference numerals 17 and 18 are comparison units, 19 is an A / D converter, 20 is a memory (M), 21 is a D / A converter, 22 is a reference voltage as an overcurrent detection reference value, 23 and 24 are switching units, 25 , 26 are reference voltages as voltage reference values, and ST is a start signal. I represents a current flowing through a load device (not shown), and V represents a detected output voltage obtained by detecting an output voltage input to the load device. The switching output unit 11 includes a switching element such as a transistor that switches a voltage applied to the primary side of the transformer (not shown), a rectifying / smoothing circuit connected to the secondary side of the transformer, and the like. The current detection unit 2 in the switching power supply unit 1 is shown as a current detection resistor 12. The output control unit 13 corresponds to the output control unit 3 in FIG. The A / D converter 19, the memory 20, and the D / A converter 21 constitute the current value storage unit 6 and the current reference value generation unit 7 in FIG.

  The detected output voltage V detected from the output voltage applied to the load device is input to the voltage display unit 15 and the comparison unit 18, the output voltage is displayed by the voltage display unit 15, and is switched by the switching unit 24 by the comparison unit 18. Compared with the reference voltage 25 or the reference voltage 26 of the voltage reference value, the error is input to the output control unit 13, and the switching output unit 11 is controlled so that the output voltage becomes a value according to the voltage reference value. When the voltage reference value is not changed, the operation is performed in the constant voltage mode in which the output voltage is controlled according to the voltage reference value.

  The comparison unit 16 compares the potentials at both ends of the current detection resistor 12 corresponding to the current I flowing through the load device, and uses the difference as a current detection value. The current display unit 14, the comparison unit 17, and the A / D converter 19, converted into a digital signal, and input to the memory 20. The memory 20 stores the digital current detection value when the start signal ST is input, and inputs the current detection value of the analog signal converted by the D / A converter 21 to the switching unit 23. Normally, the reference voltage 22 of the overcurrent detection reference value is selected by the switching unit 23 and input to the comparison unit 17. The current detection value and the overcurrent detection reference value are compared by the comparison unit 17, and the current detection value is When the value exceeds the overcurrent detection reference value, the output control unit 13 controls the switching output unit 11 to perform overcurrent protection for dropping the output voltage.

  When the start signal ST is input to the switching unit 23, the switching unit 23 detects the analog current detected by converting the reference voltage 22 of the overcurrent detection reference value by the D / A converter 21 for a predetermined period. The value is switched as a current reference value and input to the comparison unit 17. Thus, the constant current mode control state for a certain period in which the switching output unit 11 is controlled from the output control unit 13 is maintained so as to maintain the current flowing through the load device at the time of input of the start signal ST. Therefore, when the switching unit 24 switches from a low value reference voltage to a high value reference voltage using the start signal as a trigger so that the output voltage is rapidly increased, output control is performed according to the output signal from the comparison unit 18. The unit 13 performs control to increase the output voltage of the switching output unit 11 corresponding to a high reference voltage. At that time, the comparison unit 17 causes the output control unit 13 to maintain the current at the start signal input time. The switching output unit 11 is controlled in a constant current mode in which a comparison output signal is input. Thereby, generation | occurrence | production of a surge current can be prevented reliably.

  As described above, the switching unit 23 switches the reference voltage 22 of the overcurrent detection reference value from the reference voltage 22 of the overcurrent detection reference value to the current reference value indicating the current at the time of input of the start signal ST for a certain period. Incorporates functions such as a timer and one-shot multivibrator that start operation with the trigger as a trigger, and can switch back to the reference voltage 22 side of the overcurrent detection reference value after a certain period of time has elapsed since the start signal ST was input. However, various configurations can be applied. The memory 20 in the A / D converter 19, the memory 20, and the D / A converter 21 corresponding to the current value storage unit 6 and the current reference value generation unit 7 has a detected current value when the start signal ST is input. Therefore, a small-capacity configuration with the number of bits corresponding to the accuracy of the detected current value is sufficient. Further, the reference voltages 25 and 26 input to the switching unit 24 can be set as reference voltages whose set values can be changed corresponding to a desired output voltage.

It is explanatory drawing of Example 1 of this invention. It is operation | movement explanatory drawing of Example 1 of this invention. It is explanatory drawing of the principal part of Example 1 of this invention. It is explanatory drawing of a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Switching power supply part 2 Current detection part 3 Output control part 4 Voltage control part 5 Current control part 6 Current value memory | storage part 7 Current reference value production | generation part 8 Load apparatus 11 Switching output part 12 Current detection resistance 13 Output control part 14 Current display part 15 Voltage display unit 16, 17, 18 Comparison unit 19 A / D converter 20 Memory 21 D / A converter 23, 24 Switching unit

Claims (2)

In a variable voltage power supply device that supplies a stabilized output voltage to a load device and is capable of changing the output voltage.
A switching power supply for supplying an output voltage to the load device by switching control;
A voltage control unit that compares the output voltage of the switching power supply unit with a changeable voltage reference value and controls the stabilization of the output voltage of the switching power supply unit so that the output voltage corresponds to the voltage reference value; ,
A current value storage unit for detecting and storing a current supplied to the load device;
When the detected current value that detects the current supplied to the load device exceeds the overcurrent detection reference value, the output voltage of the switching power supply unit is dropped to perform overcurrent protection, and the voltage reference value is changed to change the voltage reference value. When the output voltage is changed, the switching power supply unit is controlled in a constant current mode by changing the overcurrent detection reference value to a current reference value proportional to the detected current value stored in the current value storage unit for a certain period. A variable voltage power supply device comprising: a current control unit.   A start signal for changing the output voltage of the switching power supply unit is input to the voltage control unit, the current control unit, and the current value storage unit, and the current value storage unit uses the start signal as a trigger for the load. The voltage control unit has a configuration that changes a voltage reference value to be compared with the output voltage using the start signal as a trigger, and the current control unit Detecting a current supplied to the load device by switching the overcurrent detection reference value to a current reference value corresponding to the current value stored in the current value storage unit for a certain period using the start signal as a trigger 2. The variable voltage power supply device according to claim 1, wherein the switching power supply unit is controlled in a constant current mode in comparison with a current value.

Images