JPH0624433B2 - Bipolar switching power supply - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial application field" The present invention relates to an IC under test in an IC test apparatus, for example.
The present invention relates to a bipolar switching power supply used as a power supply when looking at the voltage applied current characteristic or the current applied voltage characteristic of each terminal.

"Background of the Invention" IC tests are roughly classified into a DC test for checking the DC characteristics of terminals and an active test for checking whether or not a circuit performs a predetermined operation. The DC test is a voltage applied current measurement mode that tests whether a predetermined current flows when a predetermined DC voltage is applied to the IC terminal, and a predetermined voltage is generated at that terminal when a predetermined current is applied. There is a current applied voltage measurement mode for testing whether or not to do.

In order to perform this DC test, DC voltage sources and current sources of the number corresponding to the number of terminals of the IC under test are prepared. These DC voltage source and DC current source are required to have high-speed response characteristics in order to shorten the test time. For example, in the voltage applied current measurement mode, the applied voltage is changed stepwise at high speed, the current value at each voltage point is read at high speed, and data is taken in. Also in the current applied voltage measurement mode, the current value is changed stepwise at high speed,
The terminal voltage at each current value is read at high speed. A command for changing the voltage or the current stepwise is output as a digital signal from a controller configured by a computer or the like, and the digital signal is DA converted and given as a control signal.

As described above, high-speed response is required for the DC power supply used in the IC test device.

“Prior Art” FIGS. 4 and 5 show a conventional DC power supply.

The example shown in FIG. 4 shows the case where a DC amplifier is used. That is, a digital input signal is given to the DA converter 1,
The digital input signal is DA converted and applied to the operational amplifier 2, and the output of the operational amplifier 2 is applied to the bases of the two transistors 3 and 4 connected in a complementary manner. A case is shown in which a voltage corresponding to the voltage information given to the DA converter 1 is applied to the load 5 connected between the emitter connection point of the transistors 3 and 4 and the common potential point.

The figure shows the state of the voltage application mode, and the voltage is stabilized by the feedback circuit NF.

The example shown in FIG. 5 shows the case of a switching power supply.
That is, the DC voltage of the DC source 6 is intermittently applied to the load circuit 11 including the inductor 8, the capacitor 9 and the load 5 by the switch element 7, and the interruption ratio of the switch element 7 is controlled by the control circuit 10. By doing so, the case where the voltage applied to the load 5 is stabilized and can be changed is shown. Here, the diode D is a diode for forming a discharge passage for discharging the counter electromotive force generated in the inductor 8 when the switch element 7 is off.

“Problems to be Solved by the Invention” In the case of the circuit structure shown in FIG. 4, when the output voltage of the transistors 3 and 4 is, for example, zero, the power supply voltage is directly applied to the voltage between the collector and the emitter of the transistor 3 and 4. High power must be consumed in 3 and 4. Therefore, there is a drawback that the efficiency is low. Further, since the transistors 3 and 4 generate a large amount of heat, when a large number of power supplies (around several hundreds) are arranged in parallel, heat dissipation must be performed efficiently, which makes the heat design troublesome and increases the cost for heat dissipation. There is.

In the case of the circuit structure of the switching power supply shown in FIG. 5, since the switching element 7 only takes on and off states, the loss in the switching element 7 is small. Therefore, there is an advantage of being efficient. However, in the case of this circuit structure, when the voltage is changed in the increasing direction, the response is fast, but when decreasing the voltage, the electric energy stored in the inductor 8 and the capacitor 9 must be naturally discharged through the load 5. For this reason, there is an inconvenience that the rate of voltage decrease is slow and the response is poor.

Further, this switching power supply has a disadvantage that it can apply only a positive or negative polarity voltage to the load 5.

Therefore, the circuit structure shown in FIG. 6 can be considered. This circuit alternately applies positive and negative voltages to the load circuit 11 from the positive and negative DC sources 6A and 6B by controlling the on / off of the switches 7A and 7B, thereby changing the on / off ratios of the switches 7A and 7B. It is intended to apply a DC voltage which can be changed from a positive polarity voltage to a negative polarity voltage to the load 5 by appropriately selecting it, but when this circuit structure is adopted, for example, the switch 7A is used. Even if the switch 7B is turned on immediately after the switch 7B is turned off, the counter electromotive force generated in the inductor 8 is opposite to the electromotive voltage of the power source 6B, so that no current can flow in the circuit passing through the switch 7B. Therefore, this circuit is inoperable.

For this reason, the circuit shown in FIG. 7 can be considered. In the circuit shown in FIG. 7, each DC source 6A, 6B has a capacitor 12A,
12B is connected in parallel so that the counter electromotive force generated in the inductor 8 is made to flow to the capacitors 12A and 12B.

Now, consider a state in which the switches 7A and 7B are turned on and off at a duty of 50% in the circuit shown in FIG.

When the switch 7A is turned on, a current I ₁ flows as shown in FIG. 8A. When this current I ₁ flows through the inductor 8, electromagnetic energy is stored in the inductor 8.

Next, when the switch 7A is turned off and the switch 7B is turned on, the negative DC source 6B is connected to one end of the inductor 8. In this state, the electromagnetic energy stored in the inductor 8 is converted into electric energy, and a counter electromotive force is generated in the inductor 8. The counter electromotive force acts so as to keep the current I ₂ flowing in the same direction as the current I ₁ and consumes energy. As a result, the current I ₂ gradually decreases and eventually reaches zero. When the current I ₂ reaches zero, this time the capacitor 12B
A current I ₃ starts to flow from this, and this current I ₃ flows through the inductor 8 in the opposite direction to the current I ₂ .

That is, the current I ₂ is a current in the opposite direction to the negative DC source 6B. Therefore, the current I ₂ cannot flow through the DC source 6B, so the current I ₂ flows through the capacitor 12B. When the current I ₂ flows through the capacitor 12B, the capacitor 12B is charged with the voltage −ΔE as shown in FIG. 8E.

The voltage −ΔE charged in the capacitor 12B is the current I ₃
Is consumed by flowing the current I ₃ from the time when the current starts to flow, and immediately before the on / off relationship of the switches 7A and 7B is reversed, the terminal voltage of the capacitor 12B is the original DC source 6B.
The voltage returns to the state of -E ₂ .

When the switch 7B is turned off and the switch 7A is turned on again, a positive DC voltage is applied to the load circuit 11 again.
At this time the counter electromotive force is generated in the inductor 8 flows a current I ₄ flowing in the same direction as the current I _3.

The current I ₄ reverses its direction when passing through the zero cross point, and is taken over by the current I ₁ .

The current I ₄ passes from the load 5 through the inductor 8 to the capacitor 1
It flows into 2A. As a result, FIG.
+ ΔE is charged as shown in FIG. The + ΔE charged in the capacitor 12A is discharged when the current I ₁ starts to flow, and the voltage of the capacitor 12A returns to the original voltage + E ₁ of the DC source 6A.

In this way, the switches 7A and 7B have a duty of 50%.
In the state of operating in this state, the counter electromotive force generated in the inductor 8 can flow through the capacitors 12A and 12B, so that the operation is maintained.

However, when the duty is 50%, no voltage is applied to the load 5, so it cannot be said to be a practical state.

In order to apply the voltage to the load 5, the on / off ratio of the switches 7A and 7B may be set to a state other than 50%. For example switch 7A is to average the current I ₁ of the current I ₁ flowing through the load and to increase the state has decreased to the ON can provide a positive voltage to become large load 5 from the current I ₃ flowing through the GyakuMuko. Conversely, if the time during which the switch 7A is on is set shorter than the time during which it is off, the average value of the current I ₃ becomes larger than the average value of the current I ₁ , and a negative voltage can be applied to the load 5.

However, in the circuit shown in FIG. 7, the switches 7A and 7B are
When the on / off ratio of is set to a state other than 50%, the charging is repeated with the capacitor 12A or 12B biased, and the charging is further repeated without discharging the charged electric charge. The voltage is charged. Therefore, if the switches 7A and 7B are semiconductor devices such as transistors, the switches on the side charged with an abnormally high voltage will be damaged by the abnormal voltage. The time to this damage is almost instantaneous.

This is shown in FIG. In FIG. 9, the time T ₁ when the switch 7A is on is larger than the time T _{2 when it} is off T ₁
The case where the state is set to> T ₂ is shown. In this state, only the current I ₁ flowing from the inductor 8 toward the load 5 and the current I ₂ flowing when the energy stored in the inductor 8 is discharged.

The current I ₂ is a current flowing through the capacitor 12B when the switch 7B is on, as shown in FIG. Therefore, each time the current I ₂ flows, −ΔE is charged in the capacitor 12B, and the voltage of the capacitor 12B gradually increases in the negative direction as shown in FIG. 9E. If the switching speed of the switches 7A and 7B is, for example, a frequency of several KHz to several tens of KHz, the increasing speed of the voltage of the capacitor 12B corresponds to the switching speed, and the switch 7B is broken almost instantly. When the duty is reversed, the capacitor 12A is charged with the voltage. An abnormal voltage is generated in the capacitor 12A.

An object of the present invention is to eliminate the above-mentioned inconvenience and provide a bipolar switching power supply that operates normally without charging the capacitor.

In the present invention, a load circuit in which a capacitor and a load are connected in parallel between one end of the main inductor and a common potential point, and voltage output terminals of different polarities are connected to the common potential point. A pair of direct current sources that output positive and negative output voltages, and a pair of direct current sources connected between the voltage output terminals of opposite polarities and the other end of the main inductor that constitutes the load circuit, respectively. , A pair of switches that alternately apply positive and negative DC voltage according to the duty ratio determined according to the voltage value to be applied to this load circuit, two capacitors connected in parallel to the positive and negative DC sources, and one end Are connected to a common potential point and have an inductance value approximately equal to that of the main inductor, and a pair of switches connected between a pair of DC source and load. ON / OFF operation regardless of whether the switch is ON or OFF, and a bipolar switching power supply is configured by a switching switch that switches this auxiliary inductor to a state in which it is alternately connected in parallel to a capacitor connected in parallel to a DC source. Is.

With the configuration according to the present invention, the auxiliary inductor is switched to a state in which it is alternately connected in parallel to the two capacitors connected in parallel to the DC source. By this switching operation, energy is discharged from the capacitor whose voltage is gradually increasing to the auxiliary inductor and energy is stored in the auxiliary inductor.

The electric energy stored in the auxiliary inductor is transferred to the other capacitor at the next switching timing.

The other capacitor, receiving energy from the auxiliary inductor, releases its electrical energy towards the load circuit.

As described above, according to the present invention, the abnormal energy generated by the back electromotive force of the main inductor of the load circuit is transferred to the auxiliary inductor, and the abnormal energy is supplied to the forward current path that gives energy to the load circuit via the auxiliary inductor. Energy can be released.

Therefore, the abnormal voltage generated in the capacitor is absorbed, and the increase in the voltage is suppressed. Since the electric energy is used without waste, an efficient switching power supply can be provided.
In particular, it is possible to provide a bipolar switching power supply capable of supplying a positive and negative DC voltage to the load, and to obtain the advantage that the supply voltage can be changed at high speed.

[Embodiment] FIG. 1 shows an embodiment of the present invention. 1 in FIG.
Reference numeral 1 indicates a load circuit. The load circuit 11 is composed of a main inductor 8, a capacitor 9 and a load 5 connected in parallel between one end of the main inductor and the common potential point G.

6A and 6B represent positive and negative DC sources. Each of the positive and negative DC sources 6A and 6B has one end connected to the common potential point G and the other end connected to the load circuit 11 through the switches 7A and 7B.
Connected to one end of the main inductor 8. Positive and negative DC sources 6A and 6B have capacitors 12A and 12B respectively.
Are connected in parallel.

Reference numeral 13 indicates an auxiliary inductor. This auxiliary inductor 13
Has one end connected to the common potential point G and the other end being a switching switch 1
4A and 14B are alternately connected to the voltage supply points of the positive DC source 6A and the negative DC source 6B. That is, by switching the switching switches 14A and 14B, the auxiliary inductor 13
Is switched to a state in which the capacitors are alternately connected in parallel to the capacitors 12A and 12B.

(Operation of Auxiliary Inductor 13) Here, the operation of the auxiliary inductor 13 will be described. The switches 14A and 14B are on of the main switches 7A and 7B,
It is turned on and off regardless of the off operation. Here, for simplicity of explanation, it is assumed that the switches 14A and 14B are ON / OFF driven at a constant cycle with a duty of 50%.

Capacitors 12A and 12B, assuming that the main switches 7A and 7B are turned on and off with a duty of 50%.
The charging voltages of are in the same state.

In this state, when the switches 14A and 14B are turned on and off with a duty of 50% by the rectangular waves shown in FIGS. 2A and 2B, the currents I ₂₁ , I ₂₂ , I ₂₃ , as shown in FIG. 2C,
I ₂₄ is the capacitors 12A and 12B and the auxiliary inductor 1
Flowing through 3.

That is, the current I ₂₁ flows from the DC source 6A to the auxiliary inductor 13 with the switch 14A turned on. Current I ₂₁
Switch 14 while the current flows through the auxiliary inductor 13.
When A is turned off and the switch 14B is turned on instead, the current I ₂₂ flows through the capacitor 12B by the counter electromotive force generated in the auxiliary inductor 13. This current I ₂₂ is the current I
_Since it flows in the same direction as ₂₁ , the capacitor 12B is charged with a negative voltage −ΔE ₂₂ as shown in FIG. 2E.

When the current I ₂₂ gradually decreases and reaches zero, then the current I ₂₃ starting from the capacitor 12B starts flowing. Current I ₂₃
Is opposite to the current I ₂₂ that has been flowing. The voltage −ΔE ₂₂ charged in the capacitor 12B due to the flow of the current I ₂₃ is gradually returned to zero.

Next, when the switch 14A is turned on again and the switch 14B is turned off again, a current I ₂₄ that gradually decreases in the same direction as the current I ₂₃ flows in the auxiliary inductor 13. The source of this current I ₂₄ is the counter electromotive force of the auxiliary inductor 13.

Since the current I ₂₄ is in the opposite direction to the positive DC source 6A, it flows through the capacitor 12A and charges the capacitor 12A with + ΔE ₁₁ . When the current I ₂₄ reaches zero, this time the capacitor 1
A current I ₂₁ having a source current of 2 A flows through the auxiliary inductor 13. This current I ₂₁ is opposite to the current I ₂₄ .

Thus, every time the switching switches 14A and 14B are alternately turned on, the energy stored in the auxiliary inductor 13 on the positive side is transferred to the negative side capacitor 12B as the current I ₂₂ , and is stored in the auxiliary inductor 13 on the negative side. Energy is transferred to capacitor 12B as current I ₂₄ .

Since the description so far has been made on the assumption that the voltages of the capacitors 12A and 12B are equal, the energy transferred from the positive side to the negative side and the energy transferred from the negative side to the positive side are in equilibrium. Therefore, the energy transfer is in the state of zero subtraction.

Here, if the ON / OFF ratio of the main switches 7A and 7B is removed from the 50% state and the voltage is supplied to the load 5, either one of the capacitors 12A or 12B is charged with the voltage.

For example, if the main switch 7A is turned on for a long time in order to apply a positive voltage to the load 5, the capacitor 12B is gradually charged with a negative voltage and the voltage is gradually increased in the negative direction for the reason described above. Phenomenon occurs.

In this state, the current flowing through the auxiliary inductor 13 becomes unbalanced, and the current I ₂₃ flowing from the capacitor 12B has a relation of I ₂₃ > I ₂₁ larger than the current I ₂₁ flowing from the capacitor 12A. This state is shown in FIG. 2F. Currents I ₂₃ and I ₂₁
When the relation of I ₂₃ > I ₂₁ is satisfied, the auxiliary inductor 13
Receives a large amount of energy from the capacitor 12B and transfers the energy to the capacitor 12A. That is, the energy moving with the current I ₂₄ is larger than the energy moving with the current I ₂₂ , and the energy moves from the negative side to the positive side. The energy transferred to the positive side is released to the load circuit 11 while the switch 7A is on.

In this way, the electric energy stored in the capacitor 12B by the counter electromotive force of the main inductor 8 is transferred to the positive side capacitor 12A via the auxiliary inductor 13, and is supplied to the load circuit 11 from the capacitor 12A again.

Since a large current I _{23 is made} to flow from the capacitor 12B to the auxiliary inductor 13, the voltage charged in the negative direction is not accumulated in the capacitor 12B. Yotsute capacitor 1
2B is prevented from being charged with a negatively increasing voltage.

When a negative voltage is applied to the load 5, the switch 7A has a short ON period and the switch 7B has a long ON period. In this state, the main inductor 8 is connected to the capacitor 12A.
Is charged by the counter electromotive force from the capacitor 12A.
Voltage gradually increases in the positive direction.

However, the current I ₂₁ flowing from the capacitor 12A to the auxiliary inductor 13 increases, the energy transferred from the positive side to the auxiliary inductor 13 increases, and the energy is transferred to the negative side capacitor 12B. The energy transferred to the capacitor 12B is released to the load circuit 11 while the switch 7B is on. The energy stored in the capacitors 12A and 12B is proportional to the inductance value of the main inductor 8. Therefore, the inductance value of the auxiliary inductor 13 provided for carrying the energy is selected to be substantially equal to that of the main inductor 8.

In this way, it is possible to obtain a bipolar switching power supply that operates normally even when a voltage in both positive and negative directions is applied to the load circuit 11.

"Specific Embodiment" FIG. 3 shows a specific embodiment of the present invention. That is, the main switches 7A, 7B and the auxiliary switches 14A, 14B
The drive circuit of is specifically shown.

Reference numeral 16 is a switch drive circuit for driving the main switches 7A and 7B, and 17 is a switch drive circuit for driving the auxiliary switches 14A and 14B.

The switch drive circuit 16 can be composed of, for example, operational amplifiers 18 and 19, a triangular wave generator 21, and a gate drive circuit 22. A voltage V _in proportional to the voltage to be applied to the load 5 from the DA converter 1 is applied to, for example, the non-inverting input terminal of the operational amplifier 18. Operation to the inverting input terminal of amplifier 18 to the input voltage V _in and the balance added a DC voltage supplied to the load 5 through the feedback circuit NF. Operational amplifier 18
The output is output V _in -V _NF, the output voltage V _in -V _NF
Is applied to the non-inverting input terminal of the operational amplifier 19.

A triangular wave is applied from the triangular wave generator 21 to the inverting input terminal of the operational amplifier 19. The triangular wave is compared with V _in −V _NF output from the operational amplifier 18, and a rectangular wave is output to the output of the operational amplifier 19. The duty of this rectangular wave is the DA converter 1
Go-between changes in the input voltage V _in, which is input from the input voltage V
_The voltage corresponding to _in is applied to the load 5.

The voltage applied to the load 5 is fed back via the feedback circuit NF and compared with the input voltage V _in to maintain the voltage of the load 5 stable.

Output voltage V _OUT applied to the load 5 in the circuit t ₁ time switch 7A is turned on, t ₂ time switch 7B is turned on, a direct current source 6A, and 6B of the voltage E
And when Required by.

On the other hand, the switch drive circuit 17 on the auxiliary side includes, for example, three voltage comparators 23 and 24, an analog adder circuit 25, an operational amplifier 26, a triangular wave generator 27, and a gate drive circuit 28.
It can be configured by.

The comparison voltages + E _a and −E _b are applied to the inverting input terminals of the voltage comparators 23 and 24 from the comparison voltage sources 29A and 29B. The comparison voltages + E _a and -E _b are selected to be equal to the voltages + E ₁ and -E ₂ of the DC sources 6A and 6B.

With such a configuration, when the voltages of the capacitors 14A and 14B are equal to each other, the outputs of the voltage comparators 23 and 24 are zero, and the operational amplifier 26 is the triangular wave generator 27.
The triangular wave given by is converted into a rectangular wave with a duty of 50% and output.

Therefore, when the voltages of the capacitors 12A and 12B are equal, the switches 14A and 14B are driven on and off by a rectangular wave with a duty of 50%.

In the state in which the positive voltage is supplied to the load 5, the negative voltage is charged in the capacitor 12B for the reason described above. As a result, the voltage comparator 24 outputs a negative voltage proportional to the negative voltage, and supplies the negative voltage to the operational amplifier 26. Therefore, the threshold voltage of the triangular wave changes and the duty of the rectangular wave output from the operational amplifier 26 changes. That is, the switch 14B is kept in the ON state for a long time, and the energy stored in the capacitor 13B is taken into the auxiliary inductor 13 as much as possible.

Next, when the negative voltage is supplied to the load 5, the operational amplifier 2
On the contrary, the rectangular wave output from 6 changes to a duty in which the switch 14A is long and is in the ON state, and the capacitor 12A
The auxiliary inductor 13 operates so that a large amount of energy can be taken from the auxiliary inductor 13.

Deyutei square wave if the input voltage V _in supplied from the DA converter 1 increases output from the switch driving circuit 16 changes transiently rapidly the voltage applied to the load 5 in a positive or negative direction increase.

On the other hand, when the voltage applied to the load 5 is reduced, the on-time of the switch that supplies the current to the load circuit 11 is rapidly narrowed, and instead the on-time of the other switch becomes longer. The electric energy stored in the main inductor 8 due to the current supplied as it is has been conventionally consumed through the load. However, according to the structure of the present invention, the surplus power is stored in the capacitor through the other switch. 12A or 12
It is taken in by either one of B. Therefore, the voltage applied to the load can be rapidly reduced.

The conversion speed of the switches 14A, 14B is 7A, 7B.
It may be independent of the conversion rate of B. Yotsutte switch 7A,
It may be faster or slower than the conversion rate of 7B and may be taken at the same rate.

[Advantageous Effects of the Invention] As described above, according to the present invention, the auxiliary inductor 1
3 and switches 14A and 14B are provided, and the auxiliary inductor 1
The electric charge stored in either one of the capacitors 12A and 12B can be taken into the capacitor 3 as a current, stored in the auxiliary inductor as electromagnetic energy, and the counter electromotive force thereof can be transferred as a current to the other capacitor.

Due to this energy transfer, the abnormal voltage accumulated in one of the capacitors due to the counter electromotive force of the main inductor 8 disappears, and the switching operation is maintained. As a result, a bipolar switching power supply capable of supplying both positive and negative voltages to the load 5 can be provided.

Further, of course, when the voltage applied to the load 5 is increased in the positive and negative directions, the counter electromotive force generated in the main inductor 8 is consumed by the load 5 and is changed in the direction of decreasing the voltage. , 12B, and the voltage lowering speed becomes faster. Therefore, the voltage applied to the load 5 can be changed at a high speed, and when used as a direct current source for a direct current test of an IC test device, since it is a switching type, it generates little heat, and there is no need to consider heat dissipation. The cost can be reduced.

Further, since it is a switching type, it is possible to provide a DC test apparatus which is efficient and consumes less power.

[Brief description of drawings]

FIG. 1 is a connection diagram for explaining an embodiment of the present invention,
FIG. 2 is a waveform diagram for explaining the operation of the present invention, and FIG.
FIG. 4 is a connection diagram for explaining a specific embodiment of the present invention, FIGS. 4 to 7 are connection diagrams for explaining the conventional technique, and FIGS. 8 and 9 are diagrams for explaining the operation of the conventional technique. FIG. 6 is a waveform diagram for doing so. 5: load, 6A, 6B: DC source, 7A, 7B: switch, 8: main inductor, 9: capacitor, G: common potential point, 11: load circuit, 12A, 12B: capacitor, 1
3: auxiliary inductor, 14A, 14B: switching switch,
16, 17: Switch drive circuit.

Claims (1)

[Claims] 1. A. A load circuit in which a capacitor and a load are connected in parallel between one end of the main inductor and a common potential point, and B. C. a pair of direct current sources whose voltage output terminals having different polarities are respectively connected to a common potential point and which output positive and negative direct current voltages; The positive and negative DC voltages are applied to the load circuit by being connected between the voltage output terminals of the pair of DC sources having different polarities and the other end of the main inductor constituting the load circuit. A pair of switches that are alternately applied according to a duty ratio determined according to a power voltage value, and D. A pair of capacitors connected in parallel to the positive and negative DC sources to absorb the back electromotive force generated in the main inductor, and E. An auxiliary inductor having one end connected to the common potential point and having an inductance value substantially equal to that of the inductor; A bipolar switching power supply comprising: a pair of change-over switches that are turned on and off regardless of the operation of the pair of switches, and a pair of changeover switches that alternately connect the auxiliary inductor to one and the other of the pair of capacitors in parallel.