JP2020018121A - Forward converter type inductive load drive circuit - Google Patents

Abstract

To provide a forward converter type inductive load drive circuit that improves responsiveness when an inductive load is off and enables more efficient drive than before.SOLUTION: A forward converter type inductive load drive circuit 1X includes a first commutation switching elements (25Xa, 25Xb) arranged so as to be able to cut off a commutation circuit at secondary circuits (20Xa, 20Xb). It further includes a commutation control circuit 32 for controlling opening/closing degree and/or on/off of the first commutation switching elements (25Xa, 25Xb) when inductive loads (SOLA, SOLB) are off on the basis of a current deviation.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a forward converter-type inductive load drive circuit capable of efficiently improving the response when an inductive load is turned off as compared with the related art.

  2. Description of the Related Art Conventionally, as a switching power supply circuit for supplying a direct current to various electric / electronic devices, a forward converter having a relatively simple configuration and easy control has been frequently used together with a flyback converter. reference).

  The forward converter has a choke coil and a commutation diode on the secondary side, and when a current flows from the power supply in a state where the switching element is on, the current is induced in the secondary side coil according to the back electromotive force of the primary coil of the transformer. An electromotive force is generated, and a direct current is supplied to a load via a rectifier diode and a capacitor. At this time, since energy is stored in the choke coil, the switching element is turned off, an electromotive force is generated in the choke coil, the stored energy is released, and a current flows to the load via the commutation diode.

  A drive circuit using such a forward converter can be used for driving an inductive load such as a motor, a linear motor, or a solenoid. For example, one configured for switching drive control of a double solenoid type electromagnetic switching valve as shown in FIG. 4 can be considered.

  The forward converter-type inductive load drive circuit 100 for a double solenoid type electromagnetic switching valve turns on and off a switching element in a cycle based on a pulse signal from a pulse signal generator, and supplies a smoothed DC supplied from a power supply side. The one converted into alternating current of pulse wave by switching is transformed into a predetermined alternating voltage by a switching transformer and transmitted from the primary side to the secondary side.

  For example, in the drive circuit illustrated in FIG. 4, the switching transformer T includes two primary coils Ls1 and second secondary coils Ls2 as secondary coils having the same polarity as the primary coil. A first secondary coil that supplies alternating current from the first secondary coil Ls1 as direct current to the first solenoid (SOLA) via the secondary rectifier diode D2a and the secondary smoothing capacitor C2a. A second circuit that supplies alternating current from the second circuit and the second secondary coil Ls2 as direct current to the second solenoid (SOLB) through the secondary rectifier diode D2b and the secondary smoothing capacitor C2b. The circuit is configured by a forward converter type. That is, choke coils (Lca, Lcb) and commutation diodes (D3a, D3b) forming commutation circuits are arranged in the first and second secondary circuits, respectively. Further, even in the forward converter, since the magnetic energy is somewhat stored in the core, a coil Lp2 for returning the core energy to the power supply and consuming it is generally provided on the primary side of the switching transformer T. .

  In this drive circuit, the pulse width of the pulse signal by the pulse signal generator is adjusted based on the current command output from the current command unit based on the command signal and the result of detection on the output side to the inductive load. As a result, ON / OFF switching of the primary-side switching element FET1 is controlled. Further, the first and second secondary-side switching elements (FET2a, FET2b) disposed in the first and second secondary-side circuits are turned on and off, respectively, to switch the first solenoid (SOLA) and the second solenoid. The current supply / drive to the solenoid (SOLB) is switched and controlled.

JP-A-9-239180 JP-A-2005-76922

  In the forward converter type inductive load driving circuit as described above, when driving of the inductive load is turned off, the commutation diode commutates the back electromotive force of the inductive load, so that it takes time to reduce the current. In particular, when the load current is small, the power consumed by the resistance component of the load is small, so that the current decrease slope at the time of off is small, and the time until the current supply is completely stopped becomes long.

  Also, in the drive circuit for the electromagnetic switching valve, a carrier wave for detecting the position of the valve spool is superimposed on the signal wave of the current command, and the spool position can be detected by extracting the carrier wave component from the output side. When a carrier wave for position detection is superimposed on a minute solenoid current to detect the spool position at the time of OFF, the response of position detection is slowed because the frequency of the carrier wave cannot be increased due to the above characteristics of the forward converter. Problems arise.

  In view of the above problems, an object of the present invention is to provide a forward converter-type inductive load drive circuit that enhances responsiveness when an inductive load is turned off and enables more efficient driving than before.

In order to achieve the above object, a forward converter type inductive load drive circuit according to the first aspect of the present invention uses a smoothed DC supplied from a power supply side based on a pulse signal from a pulse signal generator (8). A switching transformer (6) for transforming a pulse wave alternating current converted by an on / off switching of a primary side switching element (5) into a predetermined AC voltage and transmitting the AC voltage from a primary side to a secondary side. A current control circuit (10X, 10Y, 10Z) having a secondary circuit that supplies alternating current transmitted to the secondary side to the inductive loads (SOLA, SOLB) as direct current,
A current command unit (50) for outputting a current command based on the command signal;
On / off switching of the primary-side switching element is controlled by a cycle of a pulse signal by the pulse signal generator determined based on a current deviation obtained from the current command and a detection result on the output side to the inductive load. And a current command circuit (30).
The secondary circuit includes a secondary rectifier diode (21a, 21b) for rectifying AC from a secondary coil having the same polarity as the primary coil of the switching transformer, and a secondary rectifier diode for further smoothing the rectified DC. Forward converter having secondary-side smoothing capacitors (22a, 22b), choke coils (24a, 24b) forming a commutation circuit, and first commutation diodes (23a, 23b) in parallel with the secondary-side smoothing capacitors. An inductive load drive circuit,
The secondary circuit further includes first commutation switching elements (25Xa, 25Xb, 25Ya, 25Yb, 25Za, 25Zb) arranged so as to be able to cut off the commutation circuit,
A commutation control circuit (32, 33, 34) for controlling the opening / closing degree and / or on / off of the first commutation switching element based on the current deviation when the inductive load is turned off. It is a feature.

  A forward converter type inductive load drive circuit according to a second aspect of the present invention is the forward converter type inductive load drive circuit according to the first aspect, wherein the commutation control circuit (32) is configured to turn off the inductive load when the inductive load is turned off. When the current deviation is negative, the first commutation switching elements (25Xa, 25Xb) are closed in proportion to the negative deviation, and the drain-source voltage of the first commutation switching element is predetermined. The first commutation switching element is controlled to be turned on at a predetermined voltage or higher.

According to a third aspect of the present invention, in the forward converter type inductive load drive circuit according to the first aspect, the commutation control circuit (33) is determined based on the current deviation. When the first commutation switching element (25Ya, 25Yb) is turned on / off by the cycle of the pulse signal generated by the second pulse signal generation device (38), when the current deviation is a minus deviation, The first commutation switching element (25Ya, 25Yb) is turned off to cut off the commutation circuit;
The secondary circuit (20Ya, 20Yb) includes a second commutation diode (26Ya, 26Yb) and a resistor (27a, 27b) arranged in parallel with the secondary-side smoothing capacitor. It has a commutation circuit.

According to a fourth aspect of the present invention, there is provided the forward converter type inductive load drive circuit according to the first aspect, wherein the first commutation switching elements (25Za, 25Zb) are provided with the commutation. It is arranged so that only the circuit can be cut off,
The secondary side circuit (20Za, 20Zb) includes a secondary side switching element (29a, 29b) for turning on / off current supply to the inductive load of the secondary side circuit,
A second commutation diode (26Za, 26Zb) forming a second commutation circuit in parallel with the choke coil, and a second commutation switching element (28a, 28b) for turning on / off the second commutation circuit. ,
The commutation control circuit (34) is configured to detect a current deviation obtained from the current command and an output-side detection result for the secondary-side switching element or the first commutation switching element disposed in the secondary-side circuit. ON / OFF switching control is performed in the cycle of the pulse signal by the second pulse signal generating device (38) determined based on the above, and when the current deviation becomes negative, the first commutation switching element (25Za , 25Zb) to turn off the current supply to the first commutation diodes (23a, 23b).
The switching transformer is configured such that when the current is not supplied from the power supply side and the primary switching element (5) is off and the secondary switching elements (29a, 29b) are turned on by the commutation control circuit. An energy recovery coil (Lp2 ') for recovering a back electromotive force generated by the inductive load via a secondary coil is provided on the primary side.

A forward converter type inductive load drive circuit according to a fifth aspect of the present invention is the forward converter type inductive load drive circuit according to any one of the first to fourth aspects, wherein the driving directions of the inductive loads are opposite to each other. A pair of solenoids, a first solenoid (SOLA) and a second solenoid (SOLB),
The switching transformer has two secondary coils, a first secondary coil (Ls1) and a second secondary coil (Ls2),
The secondary circuit includes first and second secondary circuits that supply alternating current from the first and second secondary coils to the first solenoid and the second solenoid, respectively,
The first and second secondary circuits each include a secondary rectifier diode (21a, 21b), a secondary smoothing capacitor (22a, 22b), and a choke coil (24a, 24b) forming a commutation circuit. ) And a first commutation diode (23a, 23b) in parallel with the secondary-side smoothing capacitor,
On / off control of switching elements disposed in each of the first and second secondary circuits is controlled based on a command signal, and current supply by the first secondary circuit and second secondary circuit are performed. And a solenoid switching circuit (31) for controlling the switching between the driving of the first solenoid (SOLA) and the driving of the second solenoid (SOLB) by selecting the current supply of the solenoid.

A forward converter type inductive load drive circuit according to a sixth aspect of the present invention is the forward converter type inductive load drive circuit according to any one of the first to fifth aspects, wherein a position detecting mechanism of a drive unit of the inductive load is provided. Further comprising
The position detection mechanism has a carrier generation device (41) that superimposes a high-frequency carrier for position detection on a signal wave of a current command,
Position detection for extracting the carrier frequency component for position detection from the feedback signal detected at the output side of the inductive load, and detecting the position of the drive unit based on the extraction result and a predetermined reference value It further comprises a part (40).

  In the forward converter type inductive load drive circuit according to the present invention, when the inductive load is off, the commutation circuit of the secondary circuit is shut off and the energy of the back electromotive force of the inductive load is absorbed. There is an effect that high responsiveness can be realized by shortening well. Furthermore, due to this high responsiveness, when detecting the position of the drive unit of the inductive load, even when the load current is small, the frequency of the position detection carrier to be superimposed can be increased, thereby enabling highly responsive position detection. .

1 is a schematic circuit diagram showing a configuration of a forward converter type inductive load drive circuit for a double solenoid according to a first embodiment of the present invention. FIG. 6 is a schematic circuit diagram showing a configuration of a forward converter type inductive load drive circuit for a double solenoid according to a second embodiment of the present invention. FIG. 9 is a schematic circuit diagram showing a configuration of a forward converter type inductive load drive circuit for a double solenoid according to a third embodiment of the present invention. It is a schematic circuit diagram showing an example of a conventional forward converter type inductive load drive circuit for a double solenoid. FIG. 4 is a schematic circuit diagram illustrating an inductive load driving circuit when a commutation circuit is eliminated.

  In the present invention, what is obtained by converting the smoothed direct current supplied from the power supply side to the alternating current of the pulse wave by on / off switching of the primary side switching element in a cycle based on the pulse signal from the pulse signal generator. A current control circuit having a switching transformer that transforms the voltage to a predetermined AC voltage and transmits the primary side to the secondary side, and a secondary side circuit that supplies the AC transmitted to the secondary side to the inductive load as DC. And a current command unit that outputs a current command based on the command signal, and a pulse by the pulse signal generator determined based on a current deviation obtained from the current command and a detection result on the output side to the inductive load. A current command circuit for controlling on / off switching of the primary side switching element in a cycle of a signal; and A secondary rectifier diode that rectifies AC from the secondary coil of the same polarity as the primary coil of the lance, a secondary smoothing capacitor that further smoothes the rectified DC, and a choke coil that forms a commutation circuit And a first commutation diode in parallel with the secondary-side smoothing capacitor, wherein the secondary-side circuit is configured to be capable of shutting off the commutation circuit. A commutation switching element, further comprising a commutation control circuit for controlling an opening / closing degree and / or on / off of the first commutation switching element based on the current deviation when the inductive load is turned off. It is.

  According to the above configuration, when the inductive load is turned off, the first commutation switching element is turned off by the commutation control circuit, so that the commutation circuit of the secondary circuit that has slowed down the response can be cut off. it can. At this time, the load energy charges the secondary side smoothing capacitor connected in parallel to the inductive load in the reverse direction. Therefore, the interruption time of the load current when the commutation circuit is turned off is shortened, and the energy of the back electromotive force generated in the inductive load at this time is absorbed.

  If the capacity of the secondary-side smoothing capacitor is small with respect to the load energy, the voltage increases and the capacitor may be destroyed. Therefore, it is desirable to further provide a means for absorbing energy and processing the energy of the choke coil in addition to the capacitor.

  As such a further first means, there is provided a commutation control circuit for performing control to close the first commutation switching element, which interrupts the commutation circuit, to an opening proportional to the negative deviation of the current. There is a configuration. The first commutation switching element, which is closed in proportion to the minus deviation, has a drain-source voltage (Vds) raised, and can consume the surplus current from the secondary-side smoothing capacitor and the energy of the choke coil. . In this case, the commutation control circuit turns on the first commutation switching element at Vds at which Vds is predetermined and equal to or higher than a predetermined value to recover the cutoff of the commutation circuit. It shall be controlled not to exceed the rating.

  Further, as a second means different from the above-described proportional control method, the commutation control circuit performs on / off switching control by PWM control for the first commutation switching element based on the current deviation, and at the same time, performs induction control. In the circuit configuration in which the first commutation switching element is turned off and the commutation circuit is cut off when the current deviation when the load is off is a minus deviation, the second commutation circuit is replaced with the commutation circuit by the first commutation diode to be cut off. There is a configuration in which a commutation circuit is formed. This second commutation circuit is composed of a choke coil common to the commutation circuit to be cut off, another second commutation diode and a resistor arranged in parallel with the secondary-side smoothing capacitor. In this configuration, the surplus current from the secondary-side smoothing capacitor and the energy of the choke coil when the commutation circuit is cut off when the inductive load is turned off are consumed by the resistance of the second commutation circuit.

  The above proportional control method and the circuit configuration for consuming excess energy by the second commutation circuit are effective when the inductive component of the inductive load is relatively small. However, when the inductive load is increased, the amount of heat to be processed when the commutation circuit is cut off when the inductive load is off increases, and therefore it is desirable to provide a means capable of recovering a large surplus energy.

  Then, as a third means, it is conceivable to provide an energy recovery coil on the primary side of the switching transformer to recover surplus energy. When there is no current supply from the primary side, that is, when the primary side switching element is off, the back electromotive force generated in the inductive load is converted to alternating current to the primary side via the switching transformer if there is no commutation circuit. Can be returned.

  Here, FIG. 5 shows a case where the commutation diodes (D3a, D3b) are eliminated in the conventional double solenoid forward converter type inductive load drive circuit shown in FIG. In the secondary circuit without the commutation diode, when the secondary switching element FET2a is turned on, the secondary smoothing capacitor C2a charged with the back electromotive force of the inductive load is turned on as shown by the dotted line in FIG. A current flows through the secondary coil Ls1 as a power source.

  Therefore, if on / off switching control of the secondary side switching element FET2a is performed by PWM control to convert DC from the secondary side smoothing capacitor C2a into AC, the back electromotive force generated in the secondary side coil Ls1 is An induced electromotive force is generated in the energy recovery coil Lp2 provided on the primary side, and a current flows to the primary side circuit via the primary side diode D1. In this case, in the switching transformer T, the secondary coil Ls1 becomes the primary coil, the primary coil Lp2 functions as the secondary coil, and a forward converter in the reverse direction is formed. In the switching transformer of the forward conversion, a coil for returning the core energy to the power supply is arranged on the primary side, and this can be used as the above-mentioned energy recovery coil.

  Actually, in the secondary circuit in which the secondary switching element is turned on and off by PWM control, instead of eliminating the commutation diode, a commutation circuit using the first commutation diode is provided by the first commutation switching element. Only a second commutation circuit having a second commutation diode and a second commutation switching element arranged in parallel with the choke coil may be formed while blocking only the second commutation diode.

  With this circuit configuration, when the current deviation when the inductive load is turned off becomes negative, the commutation circuit is cut off by turning off the first commutation switching element and the second commutation in the off state of the secondary side switching element. When the current switching element is turned on, the back electromotive force generated in the inductive load charges the secondary-side smoothing capacitor, and the energy of the choke coil can be commutated in the second commutation circuit. The surplus energy from the secondary-side smoothing capacitor is sent to the switching transformer when the secondary-side switching element is on. At the same time, the DC from the secondary-side smoothing capacitor is converted to AC by the on-switching control in the PWM control of the secondary-side switching element, and is transmitted from the secondary-side coil to the primary-side energy recovery coil by the switching transformer, so that the primary-side is recovered. Collected in the side circuit. Therefore, even if the surplus energy is large, an efficient inductive load stop in a short time without heat generation can be realized.

  When the inductive load according to the present invention includes a pair of solenoids of a first solenoid and a second solenoid, for example, a double solenoid type electromagnetic switching valve, the switching transformer is configured as a secondary coil as a secondary coil. It is assumed that there are two coils, one secondary coil and the second secondary coil. The secondary circuit includes first and second secondary circuits that supply alternating current from the first and second secondary coils to the first solenoid and the second solenoid, respectively.

  These first and second secondary circuits are respectively composed of a secondary rectifier diode, a secondary smoothing capacitor, a choke coil forming a commutation circuit, and a first transformer parallel to the secondary smoothing capacitor. And a current diode. The solenoid switching circuit controls on / off of the switching elements disposed in each of the first and second secondary circuits based on the command signal, and controls the supply of current by the first secondary circuit. By selecting the current supply by the second secondary circuit, the drive of the first solenoid and the drive of the second solenoid can be switched and controlled.

  The switching element that switches on and off the first and second secondary circuits for switching drive between the first solenoid and the second solenoid is as follows. A first commutation switching element that interrupts each commutation circuit is used. That is, the first commutation switching element may be arranged at a position where the secondary circuit can be shut off.

  Further, a case may be considered in which the position of the drive unit of the inductive load is detected as the inductive load drive circuit. As a position detection mechanism for this purpose, a carrier wave generator superimposes a high-frequency carrier for position detection on the signal wave of the current command, and extracts a carrier frequency component for position detection from a feedback signal detected at the output side of the inductive load. Then, from the extraction result, a change amount corresponding to an inductance change according to the position of the drive unit of the inductive load, for example, a change amount of the current amplitude or the voltage amplitude, and a drive unit of the drive unit based on a predetermined determination reference value. It is configured to include a position detection unit that detects a position.

  When the position detection mechanism detects the position of the drive unit, for example, the spool position when the solenoid of the electromagnetic switching valve is turned off, in the present invention, when the solenoid is stopped by shutting off the commutation circuit as described above. Due to its high response, even if the solenoid current is very small, high frequency can be superimposed for position detection and its components can be extracted well from the feedback signal detected at the output side. Become.

  As a first embodiment of the present invention, a schematic diagram of FIG. 1 shows a forward converter type inductive load drive circuit for a double solenoid when a commutation circuit is cut off by proportional control. The forward converter type inductive load drive circuit 1X according to the present embodiment converts the current supplied from the power supply 2 on the primary side into a smoothed DC and converts it into an AC, and converts the AC into a predetermined AC by the switching transformer 6. The voltage is converted to a voltage, transmitted from the primary side to the secondary side, and the alternating current transmitted to the secondary side is rectified and smoothed as a pair of a first solenoid (SOLA) and a second solenoid (SOLB) as an inductive load as DC. ) Is provided.

  The primary side of the current control circuit 10X has a primary side capacitor 4 and an on / off switching in a cycle based on a pulse signal from the pulse signal generator 8 to convert a direct current into an alternating current of a pulse wave to convert the direct current into an alternating current of a pulse wave. And a primary-side switching element (MOSFET) 5 for sending to the primary-side coil.

  The switching transformer 6 includes two secondary coils (Ls1, Ls2) having the same coil polarity as the primary coil Lp1. Note that a coil Lp2 and a primary-side diode 3 for returning the core energy to one power supply are also arranged on the primary side. On the secondary side of the current control circuit 10X, two secondary side circuits (20Xa, 20Xa) corresponding to the first solenoid (SOLA) and the second solenoid (SOLB) from the respective secondary coils (Ls1, Ls2). 20Xb). That is, the first secondary coil Ls1 is connected to the first solenoid (SOLA) by the first secondary circuit 20Xa, and the second secondary coil Ls2 is connected to the second solenoid by the second secondary circuit 20Xb. It is connected to a solenoid (SOLB).

  Each of the secondary circuits (20Xa, 20Xb) has a secondary rectifier diode (21a, 21b) for rectifying the AC transmitted to the secondary coil (Ls1, Ls2), and a further smoothed DC. And a secondary-side smoothing capacitor (22a, 22b) for sending to a solenoid (SOLA, SOLB). Further, a choke coil (24a, 24b) forming a commutation circuit and a first commutation diode (23a, 23b) are provided to constitute a forward converter.

  The current command unit 50 outputs a current command R based on the command signal, and the current control circuit 10X supplies a current from a power supply to the load according to the command. First, in a current command circuit 30, PID (Proportional Integral Differential) control is performed based on a deviation between a current command R and a target value based on a current feedback signal I based on a detection result on the output side from a current sensor 9 such as a detection resistor. An actual operation amount is obtained via the unit 7, an amplitude signal corresponding to the operation amount is generated, and output to the pulse signal generator 8. The primary-side switching element 5 performs on / off switching control by a pulse signal from the pulse signal generator 8 determined based on the current deviation, that is, the primary side of the switching transformer 6 is PWM-controlled. You.

  In this embodiment, the first and second secondary circuits (20Xa, 20Xb) each include a first commutation switching element (MOSFET) (25Xa, 25Xb) that can shut off a commutation circuit. The secondary circuits (20Xa, 20Xb) themselves are also arranged at positions where they can be cut off. Therefore, the first and second secondary circuits (20Xa, 20Xb) are turned on / off by the on / off control of the first commutation switching elements (25Xa, 25Xb).

  Further, based on the polarity signal included in the command signal, the first commutation switching element 25Xa of the first secondary circuit 20Xa and the first commutation switching of the second secondary circuit 20Xb are performed by the solenoid switching circuit 31. The on / off of the element 25Xb is controlled to be switched, the current is supplied to the first solenoid (SOLA) from the first secondary coil Ls1 by the first secondary circuit 20Xa, and the current is supplied to the second solenoid (SOLB). The current supply from the second secondary coil Ls2 to the second secondary circuit 20Xb is switched, and the driving of the pair of first and second solenoids (SOLA, SOLB) is switched with each other. In the case of an electromagnetic switching valve, this switches the drive direction of the valve spool in the opposite direction.

  In the drive control of the pair of first and second solenoids (SOLA, SOLB) according to the present embodiment, when one of the solenoids (SOLA or SOLB) is stopped, one of the secondary circuits (20Xa or 20Xb) performs the first rotation. When the current switching element (25Xa or 25Xb) is turned off, the commutation circuit is also cut off and the current supply to the first commutation diode (23a or 23b) is cut off. Therefore, the back electromotive force generated in the solenoid (SOLA or SOLB) charges the secondary side smoothing capacitor (22a or 22b), so that the load energy is absorbed and the slope of the current decrease of the solenoid (SOLA or SOLB) is large and short. The stop of the solenoid (SOLA or SOLB) is completed in time.

  However, when the capacity of the secondary-side smoothing capacitors (22a, 22b) is smaller than the load energy from the solenoid (SOLA or SOLB), surplus energy is stored together with the energy stored and released in the choke coil (24a or 24b). It needs to be processed. Therefore, in this embodiment, when the current deviation is negative, the proportional commutation control circuit 32 that closes the first commutation switching element (25Xa or 25Xb) is provided in proportion to the negative deviation.

  In the first commutation switching element (25Xa or 25Xb) closed by this proportional control, a drain-source voltage (Vds) is set, and excess energy is consumed. Note that the commutation control circuit 32 is set so as to control the first commutation switching element (25Xa or 25Xb) to be turned on at a certain Vds or more so as not to exceed the rating of the first commutation switching element. .

  In this embodiment, a position detecting mechanism for detecting the valve spool position when the solenoid (SOLA or SOLB) of the electromagnetic switching valve is turned off is further provided. That is, a carrier wave (sine wave or triangular wave) f1 for position detection from the carrier wave generator 41 is superimposed on the signal wave of the current command R. Then, a carrier frequency component is extracted from the feedback signal I by a position detection unit 40 provided in the current command unit 50, and a valve spool position is detected based on the extraction result and a predetermined position determination reference value.

  In the position detecting mechanism of the present embodiment, since the response when the solenoid is stopped is high as described above, even if the solenoid current is very small, for example, even when a high frequency of 0.1 to 1 kHz is superimposed as a carrier wave, the valve is detected from the feedback signal. Since the detection signal for reading the change in the position of the spool can be detected without being absorbed or deteriorated, the position of the valve spool can be detected satisfactorily.

  In the first embodiment, as means for absorbing the energy from the choke coil and the excess energy from the secondary-side smoothing capacitor when the commutation circuit is cut off, the first commutation switching element is proportional to the current minus the deviation. A case is shown in which a commutation proportional control circuit is provided which is closed. The present invention is not limited to this means. Therefore, next, as a second embodiment of the present invention, a case in which another means for consuming energy when the commutation circuit is cut off is provided in a forward converter type inductive load drive circuit for a double solenoid shown in FIG.

  The forward converter type inductive load drive circuit 1Y of FIG. 2 has a configuration common to the inductive load drive circuit 1X shown in FIG. 1 except for a part of the secondary side circuit and a part of the commutation control circuit. Therefore, parts in FIG. 2 common to FIG. 1 are denoted by the same reference numerals.

  In the present embodiment, on the primary side of the current control circuit 10Y, the DC smoothed by the primary side capacitor 4 is turned on / off in a cycle based on the pulse signal from the pulse signal generator 8 of the primary side switching element 5. It is converted into a pulse wave alternating current by switching and sent to the primary coil of the switching transformer 6.

  In the switching transformer 6, an alternating current is transmitted from the primary coil Lp1 to the two secondary coils (Ls1, Ls2) having the same polarity with a predetermined voltage. The secondary side of the current control circuit 10Y includes two secondary side circuits (20Ya, 20Ya) corresponding to the first solenoid (SOLA) and the second solenoid (SOLB) from the respective secondary side coils (Ls1, Ls2). 20Yb).

  Each of the secondary circuits (20Ya, 20Yb) includes a secondary rectifier diode (21a, 21b), a secondary smoothing capacitor (22a, 22b), and a choke coil (24a, 24a, 22b) forming a commutation circuit. 24b) and first commutation diodes (23a, 23b).

  A first commutation switching element (MOSFET) (25Ya, 25Yb) that can cut off the commutation circuit is provided in each of the first and second secondary circuits (20Ya, 20Yb). , 20Yb) themselves are also arranged at positions where they can be shut off. Therefore, on / off switching control of the first commutation switching element (25Ya, 25Yb) is performed by the solenoid switching circuit 31 based on the polarity signal of the command signal, and the first and second secondary circuits (20Ya, 20Yb), the current supply and drive to the first solenoid (SOLA) and the second solenoid (SOLB) are switched.

  Further, the on / off switching of the first commutation switching element (25Ya, 25Yb) is performed by PWM in the cycle of the pulse signal by the second pulse signal generator 38 determined based on the current deviation by the commutation control circuit 33. Controlled.

  In the present embodiment, the first and second secondary circuits (20Ya, 20Yb) have second commutation diodes (26Ya, 26Yb) and resistors (27a, 27b) forming second commutation circuits, respectively. Are provided in parallel with the secondary-side smoothing capacitors (22a, 22b).

  Therefore, in the above circuit configuration, when the current deviation is negative when the solenoid (SOLA or SOLB) is stopped, the first commutation switching element (25Ya or 25Yb) is turned off by the commutation control circuit 33, The commutation circuit is shut off. The back electromotive force generated by the solenoid (SOLA or SOLB) thereby charges the secondary-side smoothing capacitor (22a or 22b), but the excess current and the energy from the choke coil (24a or 24b) It flows through the commutation circuit and is consumed by the resistor (27a or 27b).

  As described above, also in the forward converter type inductive load drive circuit 1Y according to the present embodiment, since the solenoid back electromotive force at the time of the solenoid stop is absorbed, the current decrease gradient is large, and the solenoid stop in a short time is realized. You.

  As a third embodiment of the present invention, FIG. 3 shows a forward converter type inductive load driving circuit 1Z that can cope with a large inductive load and a large amount of heat. Parts in FIG. 3 common to FIG. 1 are denoted by the same reference numerals.

  In the present embodiment, on the primary side of the current control circuit 10 </ b> Z, the DC smoothed by the primary side capacitor 4 turns on / off the primary side switching element 5 in a cycle based on the pulse signal from the pulse signal generator 8. The pulse wave is converted into alternating current by switching, and sent to the primary coil of the switching transformer 6.

  In the switching transformer 6, an alternating current is transmitted from the primary coil Lp1 to the two secondary coils (Ls1, Ls2) having the same polarity with a predetermined voltage. The secondary side of the current control circuit 10Z includes two secondary side circuits (20Za, 20Za) corresponding to each of the first solenoid (SOLA) and the second solenoid (SOLB) from each of the secondary coils (Ls1, Ls2). 20Zb).

  Each of the secondary circuits (20Za, 20Zb) includes a secondary rectifier diode (21a, 21b) and a secondary smoothing capacitor (22a, 22b), and further includes a choke coil (24a, 24b) and first commutation diodes (23a, 23b).

  Each of the first and second secondary circuits (20Za, 20Zb) is provided with a secondary switching element (MOEFET) (29a, 29b) arranged so as to be able to cut off the secondary circuit. A first commutation switching element (MOSFET) (25Za, 25Zb) arranged so as to be able to cut off only the current circuit.

  The secondary switching elements (29a, 29b) are turned on / off based on the polarity signal of the command signal by the solenoid switching circuit 31, so that the first and second secondary circuits (20Za, 20Zb) are controlled. ), The current supply and drive to the first solenoid (SOLA) and the second solenoid (SOLB) are switched. Further, the secondary-side switching elements (29a, 29b) are subjected to on / off switching control (PWM control) at the cycle of the pulse signal by the second pulse signal generator 38 determined based on the current deviation. .

  Further, the first and second secondary circuits (20Za, 20Zb) respectively have second commutation diodes (26Za, 26Zb) forming a second commutation circuit in parallel with the choke coils (24a, 24b). ) And a second commutation switching element (MOSFET) (28a, 28b) arranged so as to be able to cut off the second commutation circuit.

  In the present embodiment, a coil Lp2 ′ for returning the core energy to the power supply is provided on the primary side of the switching transformer 6 together with the primary-side diode 3 as in the above-described embodiment. It is used as an energy recovery coil Lp2 'from the side.

  In the above circuit configuration, when the current deviation when the solenoid (SOLA or SOLB) is stopped is negative, the first commutation switching element (25Za or 25Zb) is turned off by the commutation control circuit 34 to commutate. When the circuit is cut off and the secondary-side switching element (29a or 29b) is turned off and the second commutation switching element (28a or 28b) is turned on, the reverse generated in the solenoid (SOLA or SOLB) occurs. The electromotive force charges the secondary-side smoothing capacitor (22a or 22b), and the energy of the choke coil (24a or 24b) commutates in the second commutation circuit. When the secondary-side switching element (29a or 29b) is turned on, surplus power from the secondary-side smoothing capacitor (22a or 22b) flows to the secondary-side coil (Ls1 or Ls2).

  Since the current flowing to the secondary coil (Ls1 or Ls2) is converted into an alternating current by PWM control, the primary side recovery coil is applied to the back electromotive force generated in the secondary coil (Ls1 or Ls2). An induced electromotive force is generated in Lp 2 ′, energy is transmitted, and recovered to the power supply side via the primary side diode 3.

  As described above, according to the forward converter type inductive load driving circuit 1Z of the present embodiment, since the energy recovery circuit is formed when the solenoid is stopped, even if the inductive load itself is large and the inductive component is large, the heat is generated. Without the load, the slope of decrease in the load current is increased, so that the stoppage in a short time with high responsiveness is realized with energy saving.

1X, 1Y, 1Z, 100: forward converter type inductive load drive circuit 2: power supply 3, D1: primary diode 4, C1: primary capacitor 5, FET1: primary switching element 6, T: switching transformer Lp1: primary side Coil Lp2: Primary side coil (for core energy recovery)
Lp2 ': Energy recovery coils Ls1, Ls2: Secondary coil 7: PID controller 8: Pulse signal generator 9: Current sensors 10X, 10Y, 10Z: Current control circuits 20Xa, 20Ya, 20Za: First secondary The side circuits 20Xb, 20Yb. 20Zb: second secondary circuit D2a, D2b, 21a, 21b: secondary rectifier diode C2a, C2b, 22a, 22b: secondary smoothing capacitor D3a, D3b, 23a, 23b: first commutation diode Lca, Lcb, 24a, 24b: choke coils 25Xa, 25Xb, 25Ya, 25Yb, 25Za, 25Zb: first commutation switching elements 26Ya, 26Yb, 26Za, 26Zb: second commutation diodes 27a, 27b: resistors 28a, 28b: second Commutation switching elements FET2a, FET2b, 29a, 29b: Secondary switching element SOLA: First solenoid SOLB: Second solenoid 30: Current command circuit 31: Solenoid switching circuits 32, 33, 34: Commutation control circuit 38: 2 pulse signal generator 40: position detector 41: transport Generator 50: current command unit

In order to achieve the above object, a forward converter type inductive load drive circuit according to the first aspect of the present invention uses a smoothed DC supplied from a power supply side based on a pulse signal from a pulse signal generator (8). A switching transformer (6) for transforming a pulse wave alternating current converted by an on / off switching of a primary side switching element (5) into a predetermined AC voltage and transmitting the AC voltage from a primary side to a secondary side. A current control circuit (10X, 10Y, 10Z) having a secondary circuit that supplies alternating current transmitted to the secondary side to the inductive loads (SOLA, SOLB) as direct current,
A current command unit (50) for outputting a current command based on the command signal;
On / off switching of the primary-side switching element is controlled by a cycle of a pulse signal by the pulse signal generator determined based on a current deviation obtained from the current command and a detection result on the output side to the inductive load. And a current command circuit (30).
The secondary circuit includes a secondary rectifier diode (21a, 21b) for rectifying AC from a secondary coil having the same polarity as the primary coil of the switching transformer, and a secondary rectifier diode for further smoothing the rectified DC. Secondary smoothing capacitors (22a, 22b), choke coils (24a, 24b) forming a commutation circuit, and a first commutation diode (23a) arranged in parallel with the secondary smoothing capacitor closer to the primary side. , 23b) comprising: a forward converter-type inductive load drive circuit comprising:
The secondary circuit further includes first commutation switching elements (25Xa, 25Xb, 25Ya, 25Yb, 25Za, 25Zb) arranged so as to be able to cut off the commutation circuit,
A commutation control circuit (32, 33, 34) for controlling the opening / closing degree and / or on / off of the first commutation switching element based on the current deviation when the inductive load is turned off. It is a feature.

According to a fourth aspect of the present invention, there is provided the forward converter type inductive load drive circuit according to the first aspect, wherein the first commutation switching elements (25Za, 25Zb) are provided with the commutation. It is arranged so that only the circuit can be cut off,
The secondary side circuit (20Za, 20Zb) includes a secondary side switching element (29a, 29b) for turning on / off current supply to the inductive load of the secondary side circuit,
A second commutation diode (26Za, 26Zb) forming a second commutation circuit in parallel with the choke coil, and a second commutation switching element (28a, 28b) for turning on / off the second commutation circuit. ,
The commutation control circuit (34) is configured to determine a second switching element disposed in the secondary circuit based on a current deviation obtained from the current command and a detection result on the output side. of by have rows on-off switching control in a cycle of the pulse signal the pulse signal generator (38), wherein the first commutation switching element (25Za, 25Zb) when the current deviation becomes negative the turn off the The current supply to the first commutation diodes (23a, 23b) is interrupted,
The switching transformer is configured such that when the current is not supplied from the power supply side and the primary switching element (5) is off and the secondary switching elements (29a, 29b) are turned on by the commutation control circuit. An energy recovery coil (Lp2 ') for recovering a back electromotive force generated by the inductive load via a secondary coil is provided on the primary side.

A forward converter type inductive load drive circuit according to a fifth aspect of the present invention is the forward converter type inductive load drive circuit according to any one of the first to fourth aspects, wherein the driving directions of the inductive loads are opposite to each other. A pair of solenoids, a first solenoid (SOLA) and a second solenoid (SOLB),
The switching transformer has two secondary coils, a first secondary coil (Ls1) and a second secondary coil (Ls2),
The secondary circuit includes first and second secondary circuits that supply alternating current from the first and second secondary coils to the first solenoid and the second solenoid, respectively,
The first and second secondary circuits each include a secondary rectifier diode (21a, 21b), a secondary smoothing capacitor (22a, 22b), and a choke coil (24a, 24b) forming a commutation circuit. ) And a first commutation diode (23a, 23b) disposed in parallel with the secondary side smoothing capacitor near the primary side ,
On / off control of switching elements disposed in each of the first and second secondary circuits is controlled based on a command signal, and current supply by the first secondary circuit and second secondary circuit are performed. And a solenoid switching circuit (31) for controlling the switching between the driving of the first solenoid (SOLA) and the driving of the second solenoid (SOLB) by selecting the current supply of the solenoid.

Claims (6)

A predetermined alternating current obtained by converting a smoothed direct current supplied from the power supply side into a pulse wave alternating current by on / off switching of a primary side switching element in a cycle based on a pulse signal from a pulse signal generator. A current control circuit having a switching transformer that transforms to a voltage and transmits the primary side to the secondary side, and a secondary side circuit that supplies the alternating current transmitted to the secondary side as direct current to the inductive load,
A current command unit that outputs a current command based on the command signal,
On / off switching of the primary-side switching element is controlled by a cycle of a pulse signal by the pulse signal generator determined based on a current deviation obtained from the current command and a detection result on the output side to the inductive load. And a current command circuit,
The secondary circuit, a secondary rectifier diode for rectifying AC from a secondary coil having the same polarity as the primary coil of the switching transformer, and a secondary smoothing capacitor for further smoothing the rectified DC. A choke coil forming a commutation circuit and a first commutation diode in parallel with the secondary-side smoothing capacitor, and a forward converter-type inductive load drive circuit,
The secondary circuit further includes a first commutation switching element arranged so as to be able to cut off the commutation circuit,
A forward converter type induction motor, further comprising a commutation control circuit for controlling the opening / closing degree and / or on / off of the first commutation switching element based on the current deviation when the inductive load is turned off. Load drive circuit.   The commutation control circuit, when the current deviation is negative when the inductive load is off, closes the first commutation switching element in proportion to the negative deviation. 2. The forward converter type inductive load drive circuit according to claim 1, wherein control is performed to turn on the first commutation switching element when the drain-source voltage is equal to or higher than a predetermined fixed voltage. The commutation control circuit controls on / off switching of the first commutation switching element in a cycle of a pulse signal by a second pulse signal generator determined based on the current deviation, and the current deviation is minus. When there is a deviation, the first commutation switching element is turned off to cut off the commutation circuit,
The said secondary side circuit has the 2nd commutation circuit provided with another 2nd commutation diode and resistance arrange | positioned in parallel with the said secondary side smoothing capacitor, The Claims characterized by the above-mentioned. 2. The forward converter type inductive load driving circuit according to 1. The first commutation switching element is arranged so that only the commutation circuit can be shut off,
The secondary-side circuit, a secondary-side switching element for turning on / off current supply to the inductive load of the secondary-side circuit,
A second commutation diode forming a second commutation circuit in parallel with the choke coil and a second commutation switching element for turning on and off the second commutation circuit;
The commutation control circuit is based on a current deviation obtained from the current command and an output-side detection result for the secondary-side switching element or the first commutation switching element disposed in the secondary-side circuit. On / off switching control is performed in the cycle of the pulse signal determined by the second pulse signal generation device, and when the current deviation becomes negative, the first commutation switching element is turned off to perform the first switching. Current supply to the current diode,
The switching transformer is configured such that when no current is supplied from the power supply side and the primary-side switching element is turned off and the secondary-side switching element is turned on by the commutation control circuit, a reverse voltage generated in the inductive load is generated. The forward converter type inductive load drive circuit according to claim 1, further comprising an energy recovery coil for recovering the electromotive force via the secondary coil on the primary side. The inductive load is a pair of solenoids of a first solenoid and a second solenoid whose driving directions are opposite to each other,
The switching transformer has two secondary coils, a first secondary coil and a second secondary coil,
The secondary circuit includes first and second secondary circuits that supply alternating current from the first and second secondary coils to the first solenoid and the second solenoid, respectively,
The first and second secondary circuits are respectively a secondary rectifier diode, a secondary smoothing capacitor, a choke coil forming a commutation circuit, and a first commutation in parallel with the secondary smoothing capacitor. And a diode,
On / off control of switching elements disposed in each of the first and second secondary circuits is controlled based on a command signal, and current supply by the first secondary circuit and second secondary circuit are performed. The forward converter according to any one of claims 1 to 4, further comprising a solenoid switching circuit that selects a current supply by the first and second solenoids and controls switching between driving of the first solenoid and driving of the second solenoid. Type inductive load drive circuit. Further comprising a position detection mechanism of the drive unit of the inductive load,
The position detection mechanism has a carrier generator that superimposes a high-frequency carrier for position detection on a signal wave of a current command,
Position detection for extracting the carrier frequency component for position detection from the feedback signal detected at the output side of the inductive load, and detecting the position of the drive unit based on the extraction result and a predetermined reference value The forward converter-type inductive load driving circuit according to claim 1, further comprising a unit.

Images