JP4061391B2 - Electronic load device and power regeneration method thereof - Google Patents

Description

BACKGROUND OF THE INVENTION
[0001]
The present invention relates to an electronic load device and power regeneration method, an electronic load device and to a power regeneration method capable regenerative power to be particularly flowing into the electronic load to a commercial power source or other equipment.
[0002]
[Prior art]
An electronic load device is used as a load for passing a current from the DUT to measure various electrical characteristics of the DUT, such as a fuel cell, a primary battery, a secondary battery, a capacitor, and a superconducting application device. Is used.
[0003]
Conventionally, when testing the electrical characteristics of power supply devices and batteries, resistors were used as load devices instead of actual loads. A method of consuming power by using a semiconductor element such as a transistor as a load device, which has advantages such as easy control of current and miniaturization, has come to be frequently used.
[0004]
FIG. 3 shows a configuration circuit diagram of a test apparatus for a device under test using such a conventional load apparatus. For example, the device under test 3, which is a battery, is connected to the terminals 3 a and 3 b of the electronic load 20, and changes the output voltage (Vo) of the device under test 3 and the magnitude Ii of the current flowing through the electronic load 20. Various electrical properties of the body 3 are measured.
[0005]
The electronic load 20 includes a load current setting device 201, a current detector 202 capable of direct current response, a power transistor 203, and an error amplifier 204. The current detector 202 detects and outputs a voltage value corresponding to the current value Ii flowing through the electronic load 20, and a difference between the output of the current detector 202 and the output of the load current setting device 201 is obtained by the error amplifier 204. . The output of the error amplifier 204 is input to the base of the power transistor 203, and the power transistor 203 is driven and controlled so that the difference between the two outputs becomes small. As a result, a constant current set by the load current setting unit 201 flows between the collector and emitter of the power transistor 203. Therefore, since the electronic load 20 operates at a constant current, the magnitude of the current flowing into the electronic load 20 does not change even if the voltage between the terminals 3a and 3b changes. The current flowing through the electronic load 20, that is, the current flowing through the power transistor 203 is converted into heat and consumed.
[0006]
By the way, when testing an object to be tested such as a primary battery or a secondary battery using the electronic load 20 as shown in FIG. 3, a saturation voltage exists between the collector and the emitter of the power transistor 203. The voltage Vo between both ends cannot be 0 V (zero volts). Therefore, for example, when a discharge characteristic test of a battery is performed, it is impossible to discharge until the terminal voltage becomes 0V.
[0007]
In order to solve such a problem, a circuit as shown in FIG. 4 has been proposed as an improved type of the circuit of FIG. In FIG. 4, circuit elements denoted by the same reference numerals as those in FIG. 3 indicate the same circuit elements. In the circuit shown in FIG. 4, in addition to the circuit configuration shown in FIG. 3, a bias power supply 205 having the same polarity as the terminal voltage is added to the current path in order to compensate for the saturation voltage of the power transistor 203 so that the voltage can be measured up to 0V. ing.
[0008]
[Problems to be solved by the invention]
As described above, in conventional electronic loads, the received power is consumed by converting it into heat with a power transistor or the like, so that power is consumed wastefully, especially when performing a high power load test. There is a problem that the cost increases.
[0009]
Conventionally, when this type of electronic load is configured with a switching circuit, the response time from when a control value is given to when the load current changes is as slow as about 300 μsec. For applications where the load current is changed at a high speed of about 10 μsec. I couldn't use it. For example, when measuring the internal impedance of a battery using an electronic load, there is a method of superimposing an AC signal (100 kHz) on the energized current. In such a case, with a switching power supply, since a smoothing LC filter is included in the output, high-speed response becomes difficult.
[0010]
Therefore, an object of the present invention is to regenerate the electric power that the conventional electronic load wasted as heat to a commercial power supply or other equipment to effectively use the electric power, and the terminal voltage of the device under test is zero volts or It is an object of the present invention to provide an electronic load device that operates in the vicinity thereof and also enables high-speed response and a power regeneration method using the same.
[0011]
[Means for Solving the Problems]
In order to solve the above-described problem, the electronic load device and the power regeneration method thereof according to the present invention employ the following characteristic configuration.
[0012]
(1) In an electronic load device that operates as a load of a device under test and has a semiconductor element and a bias power source connected in series to the device under test .
Load current control means for controlling a control electrode of the semiconductor element to set a load current of the electronic load device which is an output current of the semiconductor element;
Bias voltage determining means for setting a bias voltage of the bias power source according to an output voltage of the device under test so as to suppress a terminal voltage of the semiconductor element within a predetermined range;
Power regeneration means for regenerating the power of the bias power source to the outside when the output voltage of the device under test exceeds the terminal voltage of the semiconductor element ;
Ru equipped with an electronic load device.
[0013]
(2) The electronic load device according to (1), wherein the bias voltage determining means controls the terminal voltage of the semiconductor element to a minimum voltage necessary for the semiconductor element to perform a linear operation .
[0014]
(3) The electronic load device according to (1) or (2), wherein the bias voltage determining means includes a voltage detector that detects the terminal voltage of the semiconductor element .
[0015]
(4) The electronic load device according to (1) or (2), wherein the bias voltage determining means includes a voltage detector that detects a voltage of the device under test .
[0016]
(5) In a power regeneration method for an electronic load device that operates as a load of a device under test whose output voltage varies from a predetermined voltage to approximately 0 volts and includes a semiconductor element and a bias power source connected in series to the device under test,
A load current control step for controlling an output current of the semiconductor element, which is a load current of the electronic load device, to a predetermined value;
A bias power supply control step of setting a bias voltage of the bias power supply so that a terminal voltage of the semiconductor element becomes a predetermined value according to an output voltage of the device under test;
A power regeneration step for regenerating the power of the bias power source to the outside when the output voltage of the device under test exceeds the terminal voltage of the semiconductor element;
An electric load regeneration method for an electronic load device.
[0017]
(6) The bias power supply control step includes a first mode in which the output of the detection unit is multiplied by a coefficient, a second mode in which the terminal voltage of the semiconductor element is made substantially constant, and power consumption of the semiconductor element And a fourth mode for making the power consumption of the semiconductor element substantially constant and for preventing the terminal voltage of the semiconductor element from exceeding a predetermined upper limit value. (5) The power regeneration method for an electronic load device according to (5), wherein the voltage of the bias power supply is determined by
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of an electronic load device and a power regeneration method thereof according to the present invention will be described in detail with reference to the accompanying drawings.
[0022]
FIG. 1 is a circuit diagram according to a first embodiment of the present invention, which includes a commercial power source 1, an electronic load 2, and a device under test 3. In order to measure the characteristics of the device under test 3, the electronic load 2 is connected to the device under test 3, and the current flowing through the electronic load 2 is changed to measure the characteristics of the device under test 3. In addition, the power consumed inside the electronic load 2 is regenerated to the commercial power source 1 or other equipment (not shown) (not shown).
[0023]
The electronic load 2 includes a current control circuit 21 for controlling a current supplied to the electronic load 3, a current detector 22 capable of direct current response for detecting a current flowing through the electronic load 2 , a power element 23, and outputs of the current control circuit 21. an error amplifier 24 for outputting a difference between the output of the current detector 22 and a bias power source 25 of the bipolar which is serially connected to the power element 23 (bipolar), power regeneration circuit 26, detects a voltage across Vt of the electric power device 23 And a voltage control circuit 28 for controlling the terminal voltage Vb of the bias power supply 25 based on the output from the voltage detector 27 and the voltage detector 27 and the voltage setting unit 29.
[0024]
The current control circuit 21 controls and sets the current supplied to the electronic load 3. The output and the current flowing through the electronic load 2 detected by the current detector 22 are input to the input side of the error amplifier 24. The error amplifier 24 supplies a difference signal between the two input signals to the power element 23 to make the current flowing through the power element 23 constant. A control signal generated based on the voltage Vt across the power element 23 detected by the voltage detector 27 is output to the voltage control circuit 28 to the bipolar (bipolar) bias power supply 25 connected in series with the error amplifier 24. The The voltage control circuit 28 controls the terminal voltage Vb of the bias power supply 25 on the basis of the control signals from the voltage detector 27 and the voltage setting unit 29 in the manner described below.
[0025]
Incidentally, in the case of the conventional electronic load shown in FIG. 3, when the voltage of the device under test 3 is low, the terminal voltage of the device under test 3 may be set to 0 V because of the saturation voltage present in the power element 23. Can not. For example, if 0.5 V is present as the saturation voltage in the power element 23, no current can flow through the electronic load 2 when the output voltage of the device under test 3 is 0.1 V. That is, it was not possible to flow a current toward the electronic load 2 in this case overcomes the saturation voltage unless the output voltage of the test object 3 is 0.5V or more.
[0026]
Therefore, a bias power supply 25 is added to compensate for the saturation voltage of the power element 23. In this way, the output voltage of the device under test 3 can be changed from 0.1V to 0V by setting the voltage of the bias power supply 25 to -0.5V under the above conditions.
[0027]
The direction (polarity) of the bias power supply 205 is opposite to the polarity shown in FIG. 1 in order to compensate for the saturation voltage of the semiconductor element 23 when the voltage of the device under test 3 is 0V or a low voltage near 0V. Set. On the other hand, when the voltage of the device under test 3 is large, the polarity shown in FIG. 1 is used when the holding voltage (operating region range) of the semiconductor element is not too large, and most of the voltage of the device under test 3 is bias power supply 25. I am trying to take care of it.
[0028]
As described above, the voltage detector 27 detects the collector-emitter voltage (Vt) of the power element 103 and inputs it to the voltage control circuit 28. The voltage control circuit 28 is based on the magnitude of the input Vt. Thus, the terminal voltage Vb of the bias power supply 25 is controlled. More specifically, the voltage control circuit 28 is set to a minimum voltage (predetermined) necessary for the power element 23 to perform a linear operation based on the output of the voltage detector 27. The voltage Vb across the bias power supply 25 is adjusted. Here, “so as to have a minimum holding voltage” means that most of the power consumed by the electronic load 2 is borne by the bias power supply 25 of the power efficient switching system having a regeneration function, and the effect of regeneration is achieved. This is to bring out the maximum. As described above, since the power element 23 is configured to operate with the minimum holding voltage (narrow operating range), it is possible to stabilize the operating characteristics and to achieve favorable operating characteristics (high-speed operation).
[0029]
Now, the minimum voltage of the power element 23 is Vtx, and the first terminal voltage of the bias power supply 25 is Vb1. Considering the case where a voltage is applied to the terminal of the electronic load 2 in this state, when the voltage Vt detected by the voltage detector 27 is smaller than Vtx, that is, when Vt <Vtx, Vb1 is decreased to Vt1. The voltage control circuit 28 operates so that the voltage applied to is increased and Vt = Vtx.
[0030]
On the contrary, when the voltage Vt detected by the voltage detector 27 is larger than Vtx, that is, when Vt> Vtx, Vb1 is increased to decrease the voltage applied to Vt, and in this case, Vt = Vtx. The voltage control circuit 28 operates.
[0031]
There are the following three control modes as voltage control modes for controlling the voltage of the bias power supply 25.
[0032]
The first control mode is a mode in which the voltage Vt across the power element 23 is controlled to be constant. The value of Vt is determined in advance, and the terminal voltage Vb of the bias power supply 25 is always Vb = Vo−Vt. Operate.
[0033]
The second control mode is a mode in which the loss (Vt · Ii) of the power element 23 is made constant, and the operation flow is as follows.
(1) Vt is initially Vt1, and the loss Pt1 = Vt1 · Ii of the power element 23 at that time is obtained.
{Circle around (2)} A predetermined loss of the power element 23 is Pa, and if Pa <Pt1, the terminal voltage Vb of the bias power supply 25 is increased and the terminal voltage of the power element 23 is decreased to Vt2.
{Circle around (3)} In this state, the loss Pt2 = Vt2 · Ii of the power element 23 is obtained again so that this loss becomes the same value as Pa.
[0034]
The third control mode is a mode in which the loss of the power element 23 is made constant and the terminal voltage (Vt) of this element is controlled (limited). In this case, in addition to the flow operations (1) to (3) in the second control mode, a Vt limit operation is added.
[0035]
Here, the voltage control circuit 28 is composed of an analog circuit including an operational amplifier and a multiplier, and can operate at high speed. However, if the required response speed is not severe, it is possible to perform this part by digital control.
[0036]
A power regeneration circuit 26 is connected to the bias power source 25, and the power (Vb · Ii) consumed by the bias power source 25 is regenerated to the commercial power source 1. In this way, the bias power supply 25 regenerates power integrally with the power regeneration circuit 26, and the bias power supply 25 and the power regeneration circuit 26 are configured by a power efficient switching circuit in order to increase the regeneration efficiency. It is preferable.
[0037]
Of the power supplied by the device under test 3 to the electronic load 2, the power of the power element 23 (= Vt · Ii) is consumed as heat, but this Vt is kept to a minimum as described above. Most of the power (= Vb · Ii) is regenerated to the commercial power supply 1 via the power regeneration circuit 26 from the bias power supply 25 having a regeneration function.
[0038]
As described above, the bias power supply 25 is bipolar. For this reason, when the output voltage Vo of the device under test 3 is smaller than the holding voltage Vt of the power element 23, that is, when Vt> Vo, the bias power supply 25 has a negative voltage (that is, a polarity opposite to that in FIG. 1). As a result, the holding voltage Vt necessary for the optimum operation of the power element 23 can be secured. Similarly, it means that the influence of the voltage drop due to the resistance of the wiring when connecting the device under test 3 and the electronic load 2 can be eliminated.
[0039]
In the case of Vt << Vb, the value of power consumption (Vb · Ii) at the bias power supply 25 becomes very large. As a result, most of the power of the entire load is regenerated to the commercial power supply side, so that energy can be saved.
[0040]
By the way, when Vt> Vo described above, the polarity of the bias power supply 25 is negative. In this case, the power of the bias power supply 25 is not regenerated to the commercial power supply 1 but is supplied from the commercial power supply 1 to the bias power supply 25. Direction. As an example, considering the case of Vt = 2V, the compensation voltage is required to be −2V. In this way, the terminal voltage Vo of the device under test 3 can be lowered to 0V. However, since the device under test 3 does not supply 0 V output, that is, power at this time, −2 V power of the bias power source 25 must be supplied from the electronic load 2 itself, that is, the commercial power source 1.
[0041]
For this reason, power saving due to regeneration cannot be expected, but usually in such a case, since Vo is a relatively small voltage, the power is also low. Therefore, in most tests, the merit of the regenerative function of the present invention can be fully enjoyed. Therefore, even if the regenerative function cannot be regenerated as described above, the regenerative function is added to the electronic load device. Sex is not impaired.
[0042]
FIG. 2 is a circuit diagram showing a second embodiment of the present invention. 2, the same reference numerals as those in FIG. 1 denote the same components. In the present embodiment, voltage control of the bias power supply 25 is performed based on the terminal voltage of the device under test 3 detected by the voltage detector 27. This is because the voltage detection on the device under test 3 side can respond to the voltage change of the device under test 3 faster than the power detection on the power element 23 side. Furthermore, there is an advantage that a voltage drop due to connection to the electronic load can be prevented.
[0043]
There are the following three modes as voltage control modes for controlling the voltage of the bias power supply 25.
[0044]
In the first control mode, the voltage Vt across the power element 23 is controlled to be constant. The value of Vt is determined in advance, and the terminal voltage Vb of the bias power supply 25 is set to Vb = Vo− based on the output Vo of the voltage detector 27. The operation of setting to Vt is executed.
[0045]
In the second control mode, even if the terminal voltage of the electronic load 2 (= terminal voltage of the device under test 3) changes, the loss (Vt · Ii) of the power element 23 is controlled to be constant. Is as follows.
(1) The initial value of Vt is set to Vt1, and the loss Pt1 = Vt1 · Ii of the power element 23 is obtained.
{Circle around (2)} A predetermined loss of the power element 23 is Pa, and if Pa <Pt, the terminal voltage Vb of the bias power supply 25 is increased and the terminal voltage of the power element 23 is decreased to Vt2.
{Circle around (3)} In this state, the loss Pt2 = Vt2 · Ii of the power element 23 is obtained again so that the loss becomes the same value as Pa.
[0046]
In the third control mode, the loss of the power element 23 is made constant and the operation of limiting (limiting) the terminal voltage (Vt) of this element is executed. This can be realized by adding a Vt limit operation to the flow 3).
[0047]
Here, the voltage control circuit 28 is composed of an analog circuit including an operational amplifier and a multiplier and operates at high speed. However, if the required response speed is not severe, it is possible to perform this voltage control part by digital control.
[0048]
In the second embodiment, the voltage of the device under test 3 is detected via a dedicated terminal in order to prevent an error caused by a voltage drop due to connection.
[0049]
2, the voltage detector 27 is connected to both terminals 3a and 3b of the electronic load 3 as indicated by the solid line in FIG. 2, and these terminal voltages are regarded as the terminal voltage of the device under test 3 and the terminals of the device under test 3 are connected. Measure the voltage. However, when the test current flowing through the electronic load 2 is a large current such as 800 A and a low voltage of about several volts, the voltage drop due to the resistance of the conductive wire connecting the device under test 3 and the electronic load 2 is a problem. Thus, the correct voltage of the DUT 3 cannot be measured as it is. For example, even if the resistance of the connection is only 0.1 mΩ, the voltage drop is 80 mV, and if the voltage of the device under test 3 is 5 V, a voltage error of 1.6% occurs.
[0050]
Therefore, in this embodiment, in order to prevent the problem of voltage drop due to the connection, the voltage of the device under test 3 is detected via the dedicated terminals 3A and 3B as shown by the dotted lines in FIG.
[0051]
In measuring the characteristics of the device under test 3, connection resistance is not always a problem. If the device under test 3 has a high voltage, for example, 200V, even if the resistance of the connection is 1Ω, the voltage drop is 0.1V, 1V at a current of 0.1V when a current of 100mA is applied, The errors are only 0.05% and 0.5%, respectively.
[0052]
As described above, in the configuration in which voltage detection is always performed by separate connection, it can be said that it is troublesome because it is necessary to connect for voltage detection even when measuring at a level where the resistance of the connection can be ignored.
[0053]
Therefore, a switching means (not shown) such as a switch is provided to switch between 3a and 3A and 3b and 3B in FIG. 2 and take the input signal of the voltage detector 27 from 3a, 3b or 3A, 3B to measure the voltage. It is also useful to select a voltage detection method according to the level (how much measurement accuracy is obtained). In the above-described embodiment, power is regenerated to the commercial power supply, but it is needless to say that this may be another device.
[0054]
【The invention's effect】
As described above, according to the electronic load device and the power regeneration method thereof of the present invention, the combination of the semiconductor element that secures high-speed operation by narrowing the operation range and the switching power supply with the regeneration function is more effective than the conventional electronic load. Response speed is improved, and power that was previously wasted as heat can be regenerated to commercial power supplies or other equipment, so that power can be used effectively, and both high-speed response and low loss can be achieved. I was able to.
[Brief description of the drawings]
FIG. 1 is a test circuit diagram of a device under test using an electronic load circuit according to a first embodiment of the present invention.
FIG. 2 is a test circuit diagram of a device under test using an electronic load circuit according to a second embodiment of the present invention.
FIG. 3 is a test circuit diagram of a device under test using a conventional electronic load.
FIG. 4 is a test circuit diagram of a device under test using another conventional electronic load.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Commercial power supply 2, 20 Electronic load 3 Test object 21 Current control circuit 22 Current detector 23 Power element 24 Error amplifier 25 Bias power supply 26 Power regeneration circuit 27 Voltage detector 28 Voltage control circuit 29 Voltage setting part 201 Load current setting device 202 Current detector 203 Power transistor 204 Error amplifier 205 Bias power supply 3a, 3b, 3A, 3B terminal

Claims (6)

In an electronic load device that operates as a load of a device under test and has a semiconductor element and a bias power source connected in series to the device under test ,
Load current control means for controlling a control electrode of the semiconductor element to set a load current of the electronic load device which is an output current of the semiconductor element;
Bias voltage determining means for setting a bias voltage of the bias power source according to an output voltage of the device under test so as to suppress a terminal voltage of the semiconductor element within a predetermined range;
Power regeneration means for regenerating the power of the bias power source to the outside when the output voltage of the device under test exceeds the terminal voltage of the semiconductor element ;
Electronic load, characterized in that it comprises a. 2. The electronic load device according to claim 1, wherein the bias voltage determining unit controls the terminal voltage of the semiconductor element to a minimum voltage necessary for the semiconductor element to perform a linear operation . 3. The electronic load device according to claim 1, wherein the bias voltage determination unit includes a voltage detector that detects the terminal voltage of the semiconductor element . The electronic load device according to claim 1, wherein the bias voltage determination unit includes a voltage detector that detects a voltage of the device under test . In a power regeneration method for an electronic load device that operates as a load of a device under test whose output voltage changes from a predetermined voltage to approximately 0 volts and includes a semiconductor element and a bias power source connected in series to the device under test,
A load current control step for controlling an output current of the semiconductor element, which is a load current of the electronic load device, to a predetermined value;
A bias power supply control step of setting a bias voltage of the bias power supply so that a terminal voltage of the semiconductor element becomes a predetermined value according to an output voltage of the device under test;
A power regeneration step for regenerating the power of the bias power source to the outside when the output voltage of the device under test exceeds the terminal voltage of the semiconductor element;
A power regeneration method for an electronic load device, comprising: The bias power supply control step includes a first mode in which the output of the detection means is multiplied by a coefficient, a second mode in which the terminal voltage of the semiconductor element is substantially constant, and power consumption of the semiconductor element is substantially constant. And the fourth mode in which the power consumption of the semiconductor element is made substantially constant and the terminal voltage of the semiconductor element does not exceed a predetermined upper limit value alone or in combination. The power regeneration method for an electronic load device according to claim 5, wherein the voltage of the power source is determined.

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