Current detection circuit for bidirectional insulated DC / DC converter

Abstract

The present invention relates to a current detection circuit for an insulated DC / DC converter. A circuit for detecting the current in a bidirectional insulated DC / DC converter having a first converter and a second converter that each include a plurality of switching elements and are arranged on both sides of a coil for power conversion, may comprise: an alternating current sensor for detecting the alternating current in the coil; and a detector for determining the directionality of the present power conversion from the alternating current detected by the alternating current sensor and outputting a timing determination signal according to the confirmed directionality.

Description

Current detection circuit of a bidirectional isolated DC / DC converter

[0001] The present invention relates to a current detection circuit for a bidirectional insulated DC / DC converter, and more specifically, to a circuit that measures the output current of a bidirectional insulated DC / DC converter using a current converter to control a switching element of the DC / DC converter.

[0002] In general, a bidirectional isolated DC / DC converter is a device that converts direct current into alternating current using a number of switching elements, and then converts the converted alternating current back into direct current. In particular, since it has bidirectionality, it provides directionality of power conversion through switching control of each switching element.

[0003] In the past, the current of one output terminal (input terminal when the direction was different) was measured, the current conversion direction was recognized based on the value, and the power conversion direction was determined by differentiating the on / off time of the switching element based on the recognition result.

[0004] Fig. 5 is a block diagram of a current detection circuit of a conventional bidirectional insulated DC / DC converter, and Fig. 6 is a detailed block diagram of the detection unit in Fig. 5.

[0005] Referring to FIGS. 5 and 6, the conventional converter (10) is configured to include a detector (20) that detects a direct current (Iout) of one output terminal and determines a timing decision signal (Vd) that controls the switching timing of the switches (S1 to S8) of the converter (10) according to the direction of the detected direct current (Iout).

[0006] Hereinafter, the conventional configuration and operation configured as above will be described in more detail.

[0007] First, the converter (10) is composed of a first converter (11) and a second converter (12) centered on a coil (13), and the first converter (11) includes a plurality of switching elements (S1, S2, S3, S4), and the second converter (12) is also composed of a plurality of switching elements (S5, S6, S7, S8).

[0008] The bidirectional insulated DC / DC converter has an insulated configuration using a coil (13), and a first converter (11) and a second converter (12) of the same configuration are arranged around the coil (13).

[0009] The first converter (11) and the second converter (12) each have a plurality of switching elements (S1 to S4, S5 to S8), and can convert and output the input DC current of the first converter (11) side to the second converter (12) side through timing control of the switching elements.

[0010] A plurality of switching elements (S1 to S8) may be formed of power semiconductor elements, and convert the input direct current into alternating current by the switching control, or convert the alternating current into direct current on the output side and output it.

[0011] The first converter (11) and the second converter (12) can be used as the input side and the output side of the current, respectively, or conversely, as the output side and the input side.

[0012] At this time, the switching control timing of the switching element on the input side becomes faster than that on the output side, and the timing decision signal (Vd) for controlling such control timing is determined according to the direction of the detected direct current.

[0013] In the explanation below, for the convenience of explanation, the first converter (11) is described as the primary side (input side) and the second converter (12) is described as the secondary side (output side), but the opposite case can also be sufficiently understood.

[0014] The above detector (20) is a reference voltage (V REF) and the second converter (12) and a voltage comparator (21) that obtains the difference between the output voltage (Vo) of the first converter (12), and a reference current (I) using the comparison result of the voltage comparator (21) REF ) and a voltage proportional controller (22) that generates the reference current (I REF ) and a current comparator (23) that compares the output current (Iout) of the second converter (12), and a current proportional controller (24) that outputs a timing determination signal (Vd) according to the directionality of the output current (Iout) which is the output of the current comparator (23).

[0015] In this configuration, the detector (20) detects the output current (Iout), which is a direct current, to detect the directionality and determine the switch control timing of the switching elements (S1 to S4) of the first converter (11) and the switching elements (S5 to S8) of the second converter (12).

[0016] If the output current (Iout) is a positive value, it means that the converter (10) inputs current to the first converter (11) and outputs output current through the second converter (12). At this time, if the output current (Iout) changes to a negative value, it can be detected that the input side and the output side of the converter (10) having bidirectionality are switched.

[0017] That is, the second converter (12) becomes the input side and the first converter (11) becomes the output side, and at this time, for current conversion, the switching control timing of the switching elements of the second converter (12) is controlled faster than the switching control timing of the switching elements of the first converter (11).

[0018] The detector (20) is configured to detect the output current (Iout) using a current sensor of the shunt resistor or Hall sensor type.

[0019] In addition to the size of the measured current, accuracy, and unit price, the selection of a current sensor can also be an important factor in recent power conversion devices that require high power density, including the actual sensor size and circuit complexity to be used.

[0020] In particular, because a method of directly detecting direct current has been used in the past, there is a limitation in that a cheaper current transformer (CT) cannot be used.

[0021] Since each type of sensor has its own advantages and disadvantages, the inability to use a CT type current sensor in a DC / DC converter can be a disadvantage as it reduces the range of choices.

[0022] The problem that the present invention seeks to solve in consideration of the problems of the prior art as described above is to provide a current detection circuit that can control a bidirectional insulated DC / DC converter using a current sensor that detects alternating current.

[0023] In particular, the present invention aims to provide a current detection circuit capable of detecting an alternating current of unknown direction while determining the direction so as to control a DC / DC converter having bidirectionality.

[0024] A current detection circuit of a bidirectional insulated DC / DC converter according to a preferred embodiment of the present invention is a circuit for detecting current of a bidirectional insulated DC / DC converter, which includes a first converter and a second converter, each of which includes a plurality of switching elements and is arranged on both sides of a coil for power conversion, and may include an AC current sensor for detecting AC current of the coil, and a detector for confirming the directionality of current power conversion from the AC current detected by the AC current sensor and outputting a timing determination signal according to the confirmed directionality.

[0025] In an embodiment of the present invention, the AC current sensor can detect the AC current of the coil on the first converter side or the coil on the second converter side.

[0026] In an embodiment of the present invention, the detector may include a rectifier that converts an AC current detected by the AC current sensor into a DC current, a directionality determination device that generates a reference current and compares the reference current with the DC current of the rectifier whose directionality has been determined, and outputs a timing determination signal according to the result, and a directionality confirmation device that confirms the directionality according to the value of the timing determination signal and gives directionality to the DC current of the rectifier.

[0027] In an embodiment of the present invention, the directionality confirmation device may include an encoder that confirms directionality by confirming a timing determination signal, and a multiplier that applies the directionality confirmed by the encoder to the direct current of the rectifier.

[0028] In an embodiment of the present invention, the encoder may be a phase shifter.

[0029]

[0030] The present invention has the effect of improving expandability by enabling current detection using a wider variety of sensors by detecting an AC current of unknown direction from a converter unit using a CT, confirming the direction of the detected AC current, and generating a reference for switching control of a bidirectional insulated DC / DC converter.

[0031] Additionally, it has the effect of reducing the manufacturing cost of a bidirectional isolated DC / DC converter by using a cheaper AC current detection sensor.

[0032] FIG. 1 is a block diagram of a current detection circuit of a bidirectional insulated DC / DC converter according to a preferred embodiment of the present invention.

[0033] Figure 2 is a detailed block diagram of the detector in Figure 1.

[0034] Figure 3 is a waveform diagram of the detected AC current.

[0035] Figure 4 is a waveform diagram of direct current obtained by rectifying alternating current.

[0036] Figure 5 is a block diagram of a conventional bidirectional insulated DC / DC converter.

[0037] Figure 6 is a detailed block diagram of a conventional detector.

[0038] - Explanation of symbols -

[0039] 100:Converter 110:1st converter

[0040] 120: Second converter 130: Coil

[0041] 200: Detector 210: Rectifier

[0042] 220: Directional confirmation device 230: Directional determination unit

[0043] 300: AC current sensor

[0044]

[0045] To fully understand the structure and effects of the present invention, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various forms and can be modified in various ways. However, the description of the present embodiments is provided to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the present invention of the scope of the invention. In the accompanying drawings, components are illustrated in an enlarged size for convenience of explanation, and the proportions of each component may be exaggerated or reduced.

[0046] Terms such as "first" and "second" may be used to describe various components, but the components should not be limited by these terms. These terms may only be used to distinguish one component from another. For example, without departing from the scope of the present invention, a "first component" may be referred to as a "second component," and similarly, a "second component" may also be referred to as a "first component." Furthermore, singular expressions include plural expressions unless the context clearly dictates otherwise. Terms used in the embodiments of the present invention may be interpreted as having meanings commonly known to those of ordinary skill in the art, unless otherwise defined.

[0047] Hereinafter, a current detection circuit of a bidirectional insulated DC / DC converter according to an embodiment of the present invention will be specifically described with reference to the drawings.

[0048]

[0049] FIG. 1 is a block diagram of a current detection circuit of a bidirectional insulated DC / DC converter according to a preferred embodiment of the present invention, and FIG. 2 is a detailed diagram of the detector.

[0050] Referring to FIGS. 1 and 2, the converter (100) is configured to include an AC current sensor (300) that detects an AC current (Is) of a bidirectional converter (100), and a detector (200) that confirms the directionality of the AC current (Is) detected by the AC current sensor (300) and determines a timing decision signal (Vd) that serves as a reference for controlling the converter (100).

[0051] The above detector (200) is configured to include a rectifier (210) that converts the AC current (Is) detected by the AC current sensor (300) into a DC current, a directionality confirmation device (220) that provides directionality to the DC current converted by the rectifier (210), and a directionality determination device (230) that compares the DC current provided with directionality with a reference current and outputs a timing determination signal (Vd).

[0052] Hereinafter, the configuration and operation of the current detection circuit of the bidirectional insulated DC / DC converter according to a preferred embodiment of the present invention configured as described above will be described in more detail.

[0053] First, the converter (100) includes a first converter (110), a second converter (120), and a coil (130) between the first converter (110) and the second converter (120), and has an insulating structure by the coil (130).

[0054] The first converter (110) includes a plurality of switching elements (S1 to S4), and the second converter (120) is also configured to include a plurality of switching elements (S5 to S8).

[0055] The first converter (110) and the second converter (120) can be the input side or the output side of power conversion, respectively, or conversely, the output side or the input side.

[0056] The AC current sensor (300) detects the current on one side of the coil (130).

[0057] The AC current sensor (300) can detect the current on the first converter (110) side of the coil (130) or the current on the second converter (120) side.

[0058] When the first converter (110) is the input side and the second converter (120) is the output side, an alternating current flows on the first converter (110) side of the coil (130) by switching control of the switching elements (S1 to S4) of the first converter (110), and an induced alternating current also flows on the second converter (120) side of the coil (130).

[0059] At this time, the output current (Iout) is converted to direct current by selective switching of the switching elements (S5 to S8) of the second converter (120).

[0060] Unlike the example above, the same can be applied in a case where the second converter (120) acts as the input side and the first converter (110) acts as the output side.

[0061] Therefore, in the present invention, the AC current sensor (300) detects the AC current (Is).

[0062] Due to the nature of alternating current (Is), the direction of current flow cannot be detected. In the case of a bidirectional isolated DC / DC converter that operates by a switching signal for directional control, the direction of power conversion cannot be determined by detecting the alternating current alone, and thus control is not possible.

[0063] Considering these points, the detector (200) of the present invention includes a directionality confirmation device (220) that can confirm the directionality of the alternating current (Is) and apply it.

[0064] The direction confirmation device (220) may include an encoder (221) that checks the value of the timing signal (Vd), which is the output of the direction determination device (230), to determine whether it is a positive or negative value, and a multiplier (222) that determines the direction of the output current of the rectifier (210) using the code value of the encoder (221).

[0065] In addition, the detected AC current (Is) is compared with the reference current (I) which is a DC current. REF ) to compare AC current (Is) with DC current (I R ) includes a stop device (210) for conversion.

[0066] The above rectifier (210) includes a rectifier (211) to convert alternating current (Is) into direct current (I R ) and is converted into DC current (I) through a low-pass filter (212) to remove noise. R ) is filtered.

[0067] The direction determination device (230) is a reference voltage (V REF ) and the output voltage (Vo), and a voltage comparator (231) that obtains the difference between the voltage and the output voltage (Vo), and a reference current (I) using the comparison result of the voltage comparator (231). REF ) and a voltage proportional controller (232) that generates the reference current (I REF ) and a direct current (I) whose direction is determined R ) and a current proportional controller (234) that outputs a timing decision signal (Vd) according to the comparison result of the current comparator (233).

[0068] The timing decision signal (Vd) can determine the width of power conversion depending on its value.

[0069] That is, the size of the power converted during DC / DC current conversion can be determined by controlling the timing and cycle of turning on or off of switching elements.

[0070] In this configuration, the operation of the present invention will be described in more detail with specific examples.

[0071] A specific example will be described assuming that the first converter (110) is the input side and the second converter (120) is the output side. Since the present invention relates to the control of a bidirectional DC / DC converter, the operation when the second converter (120) is the input side and the first converter (110) is the output side can also be easily understood through the description below.

[0072] When DC power is supplied to the primary side through the first converter (110), an AC current flows through the coil (130) on the first converter (110) side through selective on / off control of the switching elements (S1 to S4) of the first converter (110).

[0073] At this time, due to the action of the coil (130), an alternating current (Is) also flows to the coil (130) on the secondary side, the second converter (120).

[0074] The output current (Io) becomes a direct current according to the selective turn-on or turn-off operation of the switching elements (S5 to S8) of the second converter (120) of the induced alternating current (Is).

[0075] The above AC current (Is) is detected by an AC current sensor (300) such as a CT. This is an example for explanation, and the AC current sensor (300) can be detected in the coil (130) on the first converter (110).

[0076] At this time, the AC current (Is) becomes an AC waveform as shown in Fig. 3, and therefore, its directionality is unknown.

[0077] The alternating current (Is) is rectified through the rectifier (211) of the rectifier (210) to produce direct current (I R ) is converted to .

[0078] At this time, direct current (I R ) is shown in Fig. 4.

[0079] Direct current (I R ) is filtered through a low-pass filter (212) to remove elements such as noise. At this time, the direct current (I R ) is always a positive value, so it is not possible to perform directional control of a bidirectional DC / DC converter using it.

[0080] The encoder (221) of the direction confirmation device (220) checks the value of the timing decision signal (Vd), which is the output of the direction decision device (230), to determine whether it is a positive or negative value.

[0081] At this time, the encoder (221) can use a phase shifter, and if it determines the code by checking the timing decision signal (Vd), which is a voltage value, it can be applied to the present invention regardless of its configuration.

[0082] Next, the multiplier (222) generates the direct current (I) described above. R ) applies the code value of the above coder (221) and provides it to the direction determination device (230).

[0083] The voltage comparator (231) of the direction determination device (230) is a reference voltage (V REF ) and the output voltage (Vo) of the second converter (120) are calculated, and the voltage proportional controller (232) calculates the reference current (I) that compensates for the comparison result of the two voltages. REF ) is generated and printed.

[0084] The current comparator (233) is a reference current (I REF ) and a direct current (I) whose direction is determined R ) are compared, and the current proportional controller (234) outputs a timing decision signal (Vd) according to the comparison result.

[0085] At this time, the timing decision signal (Vd) is a signal that determines the switching timing of the switching elements (S1 to S4) of the first converter (110) on the input side and the switching elements (S5 to S8) of the second converter (120) on the output side, and becomes a positive or negative value depending on the direction of the detected current.

[0086] The above timing determination signal is provided to a gate driving circuit (not shown in the drawing) that drives each switching element (S1 to S8), and the converter (100) operates by determining the direction of power conversion by driving the gate driving circuit.

[0087] Through this configuration, the present invention can detect an alternating current while confirming its directionality, and can control a bidirectional insulated DC / DC converter by confirming the directionality.

[0088] While the embodiments of the present invention have been described above, they are merely exemplary, and those skilled in the art will understand that various modifications and equivalent embodiments are possible. Therefore, the true scope of technical protection of the present invention should be defined by the following claims.

[0089] The present invention relates to a current detection circuit of a bidirectional insulated DC / DC converter that can confirm the direction of power conversion for AC power using natural laws, and has industrial applicability.

Claims

1. In a circuit for detecting the current of a bidirectional insulated DC / DC converter, each of which includes a plurality of switching elements and includes a first converter and a second converter arranged on both sides of a coil for power conversion, An AC current sensor that detects the AC current of the above coil; and A current detection circuit of a bidirectional insulated DC / DC converter including a detector that confirms the direction of current power conversion from the AC current detected by the AC current sensor and outputs a timing determination signal according to the confirmed direction.

2. In paragraph 1, The above AC current sensor, A current detection circuit of a bidirectional insulated DC / DC converter characterized by detecting an alternating current of the coil on the first converter side or the coil on the second converter side.

3. In paragraph 1, The above detector, A rectifier that converts the AC current detected by the above AC current sensor into DC current; A direction determination device that generates a reference current, compares the reference current with the direct current of the rectifier whose directionality has been determined, and outputs a timing determination signal according to the result; and A current detection circuit of an insulated DC / DC converter including a directionality confirmation device that confirms directionality according to the value of the timing decision signal and imparts directionality to the direct current of the rectifier.

4. In paragraph 3, The above directional confirmation device is, An encoder that verifies directionality by checking the timing decision signal; and A current detection circuit of an insulated DC / DC converter including a multiplier that applies the directionality identified in the above encoder to the direct current of the above rectifier.

5. In paragraph 4, The above coder is, A current detection circuit for an isolated DC / DC converter characterized by being a phase shifter.

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