JP6240511B2 - Electronic control unit - Google Patents

Description

  The present invention relates to an adjustment mechanism using an electromagnet and an electromagnetic coil drive control device used in an electric motor, and more particularly to an electromagnetic coil drive control device supplied with electric power from a DC power source.

  For example, automobiles are required to improve the fuel consumption (fuel consumption) of an internal combustion engine in response to environmental problems and exhaust gas emission regulations, as well as heightened awareness of energy conservation and concerns about resource depletion. For this purpose, by increasing the combustion efficiency of the internal combustion engine, combustion is performed with less fuel, and exhaust harmful components are further reduced.

  As an example of increasing the combustion efficiency of an internal combustion engine, a valve timing control device (VTC: Valve Timing Control) that optimizes the opening / closing timing of intake valves and exhaust valves based on the rotational speed of the internal combustion engine and the intake air amount (load) is known. It has been. This valve timing control device is equipped with a hydraulic mechanism that rotates the camshaft relatively, and controls the opening of the hydraulic control valve using an electromagnet to adjust the oil amount of the hydraulic mechanism to open and close the intake valve and exhaust valve The timing is changed.

  In addition to this valve timing control device, a shift control valve used in an automatic transmission, an electronic throttle control device provided in an intake passage, and the like are used to improve fuel efficiency. These are mainly driven by an electromagnet or an electric motor, and these are driven and controlled by electric power supplied to an electromagnetic coil. Thus, in order to operate the mechanism part of a motor vehicle, the drive control apparatus of the electromagnetic coil which controls the electric power which flows into the electromagnet or the electromagnetic coil of an electric motor becomes an essential structure.

  For example, as a drive control device for driving an electromagnetic coil, as disclosed in Japanese Patent Application Laid-Open No. 2006-35190 (Patent Document 1), a low-side switch is provided in the electromagnetic coil, and the electromagnetic coil is opened and closed by opening and closing this switch. The flowing current is controlled. This Patent Document 1 describes a method of shortening the decay time of induced current generated in an electromagnetic coil for the purpose of suppressing the temperature rise of the electromagnetic coil.

JP 2006-351910 A

  By the way, in an electromagnetic coil drive control device that drives and controls an electromagnetic coil, when the electromagnetic coil is driven to an excited state or a non-excited state by turning on / off the current flowing through the electromagnetic coil, the electromagnetic coil is connected to the positive electrode of the DC power supply. There is a phenomenon that conduction noise caused by on / off of a current flowing through an electromagnetic coil is generated in a wiring such as a cable and a substrate pattern.

  In the prior art, a method of absorbing conduction noise by arranging a large-capacitance capacitor in a wiring is general. However, in recent years, there has been a strong demand for downsizing a large-capacitance capacitor and efficiently suppressing conduction noise for reasons such as downsizing of an electromagnetic coil drive control device.

  An object of the present invention is to provide an electromagnetic coil drive control device capable of efficiently suppressing conduction noise while reducing the capacitance of a capacitor in order to meet such a demand.

  A feature of the present invention is that a capacitor and an impedance element are arranged in series on a connection line connecting a positive electrode line and a negative electrode line of a DC power supply, and connected to a connection line between the capacitor and the impedance element and a positive electrode side of the DC power supply. Connect the opposite end of the electromagnetic coil via a freewheeling diode, and connect the connecting line between the freewheeling diode and the end of the electromagnetic coil with the positive line or the negative line with a connecting line with a switching element. It is in place. Here, when the switching element is connected to the positive line, it becomes a high-side switch, and when it is connected to the negative line, it becomes a low-side switch.

  According to the present invention, the conduction noise caused by the drive current of the electromagnetic coil can be suppressed by the impedance element, and the capacitance of the capacitor can be further reduced. Therefore, the drive control device for the electromagnetic coil can be downsized.

It is a circuit diagram which shows the circuit structure of the drive control apparatus of the electromagnetic coil which becomes the 1st Embodiment of this invention. It is explanatory drawing which shows the change state of the voltage of the electromagnetic coil for performing the description regarding the conduction noise of the drive control apparatus of the conventional electromagnetic coil, the electric current of the freewheeling diode, the voltage of the capacitor | condenser, the electric current, and the power supply voltage. FIG. 3 is an explanatory diagram showing changes in the electromagnetic coil voltage, current, freewheeling diode current, capacitor voltage, current, and power supply voltage for explaining the conduction noise of the electromagnetic coil drive control device shown in FIG. 1. is there. It is explanatory drawing which showed the noise spectrum for comparing with the drive control apparatus of the electromagnetic coil shown in FIG. 1, and the drive control apparatus of the conventional electromagnetic coil. It is the characteristic figure which showed the ripple voltage of the power supply of the drive control apparatus of the conventional electromagnetic coil. It is the characteristic view which showed the ripple voltage of the power supply of the drive control apparatus of the electromagnetic coil shown in FIG. It is explanatory drawing which shows the relationship between the electric current which flows into the solenoid with respect to the resistance of an impedance element, and a ripple voltage. It is explanatory drawing which shows the relationship between the electric current which flows into the solenoid with respect to resistance of an impedance element, and loss. It is explanatory drawing of the circuit element which shows the 1st example of an impedance element. It is explanatory drawing of the circuit element which shows the 2nd example of an impedance element. It is explanatory drawing of the circuit element which shows the 3rd example of an impedance element. It is explanatory drawing of the circuit element which shows the 4th example of an impedance element. It is explanatory drawing of the circuit element which shows the 5th example of an impedance element. It is explanatory drawing of the circuit element which shows the 6th example of an impedance element. It is a circuit diagram which shows the circuit structure of the drive control apparatus of the electromagnetic coil which becomes the 2nd Embodiment of this invention. It is a circuit diagram which shows the circuit structure of the drive control apparatus of the electromagnetic coil which becomes a modification of 2nd Embodiment shown in FIG. It is explanatory drawing which shows the loss (simultaneous change) when the impedance element of the drive control apparatus of the electromagnetic coil which becomes the 2nd Embodiment of this invention is used in common. It is explanatory drawing which shows the loss (half-cycle shift) when the impedance element of the drive control apparatus of the electromagnetic coil which becomes the 2nd Embodiment of this invention is used in common. It is explanatory drawing which shows the timing production | generation (fixed shift) of the drive control apparatus of the electromagnetic coil which becomes the 2nd Embodiment of this invention. It is a block diagram which shows the timing generation (fixed shift) of the drive control apparatus of the electromagnetic coil which becomes the 2nd Embodiment of this invention. It is explanatory drawing which shows the timing production | generation (cyclic shift) of the drive control apparatus of the electromagnetic coil which becomes the 2nd Embodiment of this invention. It is a block diagram which shows the timing production | generation (cyclic shift) of the drive control apparatus of the electromagnetic coil which becomes the 2nd Embodiment of this invention. It is a circuit diagram which shows the circuit structure of the drive control apparatus of the conventional electromagnetic coil. It is explanatory drawing which shows the loss (simultaneous change) when each impedance element of the drive control apparatus of the electromagnetic coil which becomes the 2nd Embodiment of this invention is used separately. It is explanatory drawing which shows the loss (half-cycle shift) when each impedance element of the drive control apparatus of the electromagnetic coil which becomes the 2nd Embodiment of this invention is used separately.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiments, and various modifications and application examples are included in the technical concept of the present invention. Is also included in the range.

  A first embodiment of the present invention will be described in detail with reference to FIG. In FIG. 1, reference numeral 1 is an electromagnetic coil drive control device targeted by the present invention, and a circuit element for controlling the current flowing through the electromagnetic coil 3 is provided therein. The electromagnetic coil 3 is used in various adjustment mechanisms. In this embodiment, the electromagnetic coil of a hydraulic control valve used in the valve timing control device is shown. The hydraulic control valve is a control valve whose position linearly changes depending on the magnitude of current, and can control the position of the mover by an average current value that changes according to the on / off ratio (duty) of the drive current. In general, this type of direct acting electric device is called a solenoid, and hence the electromagnetic coil 3 will be called a solenoid 3 hereinafter. In this figure, circuit elements for driving the solenoid 3 are shown, and the description of other circuit elements is omitted.

  The electromagnetic coil drive control device 1 is provided with terminals T1, T2, and T3. The terminal T1 is connected to a DC power source 2, for example, a positive terminal of an in-vehicle battery, and the terminal T2 is connected to a negative terminal of the DC power source 2. The terminal T3 is connected to the positive terminal of the DC power source 2 through the solenoid 3. The solenoid 3 is a coil for constituting an electromagnet, and the position of the hydraulic control valve is changed by the current flowing through the solenoid 3, and the amount of oil in the hydraulic mechanism can be adjusted. This type of mechanism is well known and will not be described in detail here.

  The terminal T1 is connected to the positive electrode line L1 in the electromagnetic coil drive control device 1, and the terminal T2 is connected to the negative electrode line L5 in the electromagnetic coil drive control device 1. The positive electrode line L1 and the negative electrode line L5 are connected by a connection line L3, and the impedance element 7 and the capacitor 6 are arranged and connected in series from the positive electrode line L1 to the negative electrode line L5 in the middle of the connection line L3. . One end of the connection line L3 between the capacitor 6 and the impedance element 7 and the solenoid 3 is connected by a connection line L2, and a freewheeling diode 5 is disposed on the connection line L2. The cathode side of the return diode 5 is connected to a connection line L3 between the capacitor 6 and the impedance element 7, and the anode side of the return diode 5 is connected to one end of the solenoid 3.

  Here, various capacitors including an electrolytic capacitor can be used as the capacitor 6, but a ceramic capacitor is used in this embodiment. This is because a ceramic capacitor has a small resistance value and is suitable for suppressing the generation of noise.

  Further, the anode side of the return diode 5 and one end of the solenoid 3 and the negative electrode line L5 are connected by a connection line L4, and a switching element 4 as a low-side switch is connected to the connection line L4. The switching element 4 is an FET, the drain side of the switching element 4 is connected between the anode side of the freewheeling diode 5 and one end of the solenoid 3, and the source side of the switching element 4 is connected to the negative electrode line L5.

  The positive side of the DC power supply 2 is connected to other circuits in the drive control device 1 of the electromagnetic coil via the positive line L1 and the GND side is connected to the other circuit in the electromagnetic coil drive control device 1 via the negative line L5. Since it is not related to the present invention, a detailed description is omitted.

  In the above, when a predetermined control signal is applied to the gate of the switching element 4, the switching element 4 is turned on, the drain voltage becomes 0V, and a current flows through the solenoid 3. The current flowing through the solenoid 3 is such that when the switching element 4 is in the ON state, the DC power source 2 and the solenoid 3 are in a closed circuit, and a drive current flows through the solenoid 3. This drive current increases with time, and electrical energy is stored in the inductance of the solenoid 3.

  On the other hand, when the switching element 4 transitions to the OFF state, the solenoid 3, the freewheeling diode 5, and the impedance element 7 are closed and free wheel current flows. The free wheel current flows so as to release the electrical energy stored in the inductance of the solenoid 3, and the current decreases with time. The freewheel current is a current that flows when the solenoid 3, the return diode 5, and the impedance element 7 are in a closed circuit when the switching element 4 is in the OFF state. When the switching element 4 is in the ON state, the voltage on the anode side of the freewheeling diode 5 becomes 0V. As a result, the voltage on the cathode side becomes high, so that no freewheel current flows.

  In addition to this, when the switching element 4 is in the OFF state, the DC power source 2, the solenoid 3, the freewheeling diode 5 and the capacitor 6 become a closed circuit, and electric charge is stored in the capacitor 6. Conversely, when the switching element 4 is in the on state, no current flows through the free wheeling diode 5, so that the charge stored in the capacitor 6 flows out toward the impedance element 7 when the switching element 4 is in the off state. The electric charge stored in the capacitor 6 is added to the positive electrode line L1. In this embodiment, since the impedance element 7 is disposed between the capacitor 6 and the positive electrode line L1, the electric charge stored in the capacitor 6 is It is consumed by the impedance element 7 and is not superimposed on the positive electrode line L1. As a result, generation of a ripple voltage in the positive electrode line L1 is suppressed, and conduction noise can be reduced. This ripple voltage is high-frequency conduction noise corresponding to the on / off of the solenoid 3.

  For comparison with the present embodiment, FIG. 14 shows a conventional electromagnetic coil drive control apparatus in which the impedance element 7 is not provided. As can be seen from FIG. 14, the difference from the present embodiment is a portion surrounded by a rectangular dotted line. As shown in FIG. 14, the conventional electromagnetic coil drive control device has a circuit configuration in which the connection point between the freewheeling diode 5 and the capacitor 6 is directly connected to the positive line L1 on the power supply side via the connection line L3. . For this reason, it was necessary to increase the capacity of the capacitor 6 in order to suppress the ripple voltage. Therefore, the subject that the physique of the electronic control apparatus 1 became large as much as the capacity | capacitance of the capacitor | condenser 6 became large had arisen.

  On the other hand, since the ripple voltage can be suppressed by the impedance element 7 in this embodiment, the conduction noise can be efficiently suppressed and the capacity of the capacitor 6 can be reduced, so that the size of the electronic control device 1 can be reduced. become able to.

  Next, the operation of the electromagnetic coil drive control device according to the first embodiment shown in FIG. 1 and the operation of the conventional electromagnetic coil drive control device shown in FIG. 14 will be compared and described. 2A and 2B show the voltage of the DC power source 2 (in-vehicle battery is used in this embodiment), the inductance of the coil of the solenoid 3 is 15 mH, the resistance is 8Ω, and the driving frequency of the switching element 4 is 10 kHz. In this example, the duty is 50%.

  FIG. 2A shows the conventional electromagnetic coil drive control device shown in FIG. 14 in which the capacity of the capacitor 6 is 220 μF, and FIG. 2B shows the electromagnetic coil drive control device shown in FIG. In this example, the impedance element 7 is a resistor having a resistance value of 6Ω at 10 μF. Thus, in this embodiment, the capacity of the capacitor 6 is 1/22. Hereinafter, the behavior of the current and voltage of each circuit element will be described.

(1) Solenoid voltage shown in FIGS. 2A and 2B The voltage of the solenoid 3 is a voltage on the drain side of the switching element 4. The on / off state when the driving frequency is 10 kHz and the duty is 50% is shown. When the switching element 4 is on, the drain voltage is about 0V and current flows through the solenoid 3, and when the switching element 4 is off, the drain voltage is about 14V and the current of the solenoid 3 is cut off. The

(2) Solenoid current shown in FIGS. 2A and 2B The solenoid current is a current on the drain side of the switching element 4. When the switching element 4 is in the ON state, the DC power supply 2 and the solenoid 3 become a closed circuit, and a drive current flows through the solenoid 3. This drive current increases with time, and electrical energy is stored in the inductance of the solenoid 3. Further, when the switching element 4 is in the OFF state, the solenoid 3, the return diode 5 and the impedance element 7 become a closed circuit, and free wheel current flows. The electric current stored in the inductance of the solenoid 3 is discharged, and the current decreases with time. Since the conventional electromagnetic coil drive control device does not include the impedance element 7, the charge of the capacitor 6 is not consumed as will be described later.

(3) Freewheel current shown in FIGS. 2A and 2B The freewheel current is a current that flows when the solenoid 3, the return diode 5 and the impedance element 7 are closed when the switching element 4 is in an off state. The current on the cathode side of the reflux diode 5 is shown. When the switching element 4 is in the ON state, the anode voltage of the freewheeling diode 5 becomes 0V, so that the cathode voltage becomes high so that it does not flow. Also in this case, since the conventional electromagnetic coil drive control apparatus is not provided with the impedance element 7, the charge of the capacitor 6 is not consumed as will be described later.

(4) Capacitor current shown in FIGS. 2A and 2B When the switching element 4 is in the OFF state, the DC power supply 2, the solenoid 3, the freewheeling diode 5, and the capacitor 6 become a closed circuit, and charges are stored in the capacitor 6. When the switching element 4 is in the ON state, no current flows through the freewheeling diode 5, so that the electric charge stored up to that time flows out toward the impedance element 7. In the figure, the current between the capacitor 6 and the connection point (VC (illustrated)) of the connection line L2 and the connection line L3 is shown. Since the conventional electromagnetic coil drive control device does not include the impedance element 7. The electric charge of the capacitor 6 flows out toward the positive electrode line L1.

(5) Capacitor voltage shown in FIGS. 2A and 2B The voltage (VC point) of the capacitor 6 is 14V of the DC power supply 2 in a steady state, and is superposed by a voltage changed by the capacitor current. In the figure, it is a voltage at a connection point (in VC (illustrated)) between the connection line L2 and the connection line L3. This voltage is generally obtained from V = IT / C from Q = IT and Q = CV, and is converted into a current. It can be seen that Q is a charge, C is a capacitance, V is a voltage between electrodes, I is a current flowing between the electrodes, and T is time.

In the conventional electromagnetic coil drive control device shown in FIG. 2A, the capacitor current is about 0.4 A, the time is about 50 μs, the capacitance is 220 μF, and the capacitor voltage is
V = 14 + 0.4 × 50/220 = 14 + 0.1 = 14.1 (V)
It becomes.

In the electromagnetic coil drive control device according to this embodiment shown in FIG. 2B, the capacitor current is about 0.4 A, the time is about 50 μs, the capacitance is 10 μF, and the capacitor voltage is
V = 14 + 0.4 × 50/10 = 14 + 2.5V = 16.5 (V)
It becomes.

(6) Power supply voltage shown in FIGS. 2A and 2B The power supply voltage is the voltage of the positive line L1 or the terminal T1. In the conventional electromagnetic coil drive control device of FIG. 2A, the magnitude of the ripple voltage of the power source is obtained from the difference between the maximum voltage and the minimum voltage, and in this example is as small as several hundred mV. This is a circuit configuration in which the electric charge of the capacitor 6 is directly transmitted to the positive electrode line L1, but the voltage fluctuation is small because the capacitance of the capacitor 6 is set to be as large as 220 μF. However, when the capacitor 6 is increased in this way, the physique of the electromagnetic coil drive control device is increased, which is not preferable.

  On the other hand, it can be seen that the ripple voltage of the power supply is as small as several hundred mV in the electromagnetic coil drive control apparatus of this embodiment of FIG. 2B. The reason for this is that even if the capacitance of the capacitor 6 is considerably reduced, since the impedance element 7 is disposed between the capacitor 6 and the positive electrode line L1, the voltage generated in the capacitor 6 (in this case, about 2.5V) This is because they are consumed by the impedance element 7 and thus do not appear on the positive line L1. For this reason, while suppressing conduction noise and the capacity | capacitance of the capacitor | condenser 6 can be made small, the physique of the drive control apparatus of an electromagnetic coil can be made small.

  If the impedance of the wiring between the DC power supply 2 and the impedance element 7 is 0Ω, the voltage at the terminal T1 is fixed at 14V, and the ripple voltage of the power supply becomes 0V. However, in practice, there is a slight impedance because there is a wiring inductance or a wiring resistance between the DC power source 2 and the impedance element 7. In this case, a voltage corresponding to the wiring impedance and the voltage dividing ratio of the impedance element 7 is observed at the terminal T1. For example, assuming that the inductance of the wiring is 10 μH, the wiring impedance (reactance) is about 0.6Ω. The ripple voltage when the impedance element 7 is 6Ω and the voltage of the capacitor 6 fluctuates by 2.5 V is V = 2.5 × 0.6 / (0.6 + 6) = 0.2 V, which can be sufficiently reduced.

  As described above, the conventional electromagnetic coil drive control device has a configuration in which conduction noise is suppressed by the large-capacitance capacitor 6, and the conduction noise can be suppressed. There was a problem that the physique of became large.

  On the other hand, according to the present embodiment, conduction noise is sufficiently suppressed by using the impedance element 7 and the capacitor 6, and the capacitance of the capacitor 6 can be considerably reduced. Can be reduced.

  Next, the standard of conduction noise will be briefly described. As an international standard, there is a standard CISPR25 (1995) “Interference wave limit value and measurement method for in-vehicle receiver protection” prepared by the International Radio Interference Special Committee (CISPR). The CISPR25 standard relates to radio interference waves in the frequency band of 150 kHz to 1,000 MHz and is applied to electronic components used in automobiles. The recommended value is determined to protect the receiver in the same car from the interference generated from the parts and modules in the car. The receivers to be protected are radio, television and radio equipment. is there.

  And based on this reference | standard, the noise spectrum of the Example shown in FIG. 1 and the prior art example shown in FIG. 14 was measured. This noise spectrum is noise derived from the voltage of the power supply line between the terminal T1 and the DC power supply 2. As shown in FIG. 3, the frequency ranged from 100 kHz to 500 kHz. In the conventional example shown in FIG. 14, the capacitance of the capacitor 6 is set to 220 μF, and in the present embodiment shown in FIG. 1, the capacitance of the capacitor 6 is set to 10 μF, the impedance element 7 is a resistor, and the resistance value is set to 6Ω. . The noise level at a measurement frequency of 100 kHz is 69 dBμV in the conventional example (in the broken line (illustrated)) and 64 dBμV in the present example (in the solid line (illustrated)). Further, the noise level becomes higher as the measured frequency becomes higher. Although it becomes smaller, it can be understood that the noise level is always kept small in this embodiment as compared with the conventional example.

  Thus, in contrast to the noise suppression effect (noise level) indicated by the broken line achieved in the conventional example, according to the present embodiment, the noise suppression effect is further promoted as indicated by the solid line, and the noise is reduced compared to the conventional example. You can see that the level is small.

  Further, FIG. 4A shows the magnitude of the ripple voltage of the conventional example shown in FIG. 14, and FIG. 4B shows the magnitude of the ripple voltage of this embodiment shown in FIG. In contrast to the ripple voltage of 0.4 V in the conventional example, according to this embodiment, the ripple voltage is reduced to 0.2 V, the magnitude of the ripple voltage is about half, and the noise level It can be seen that is effectively suppressed.

  FIG. 5 shows the relationship between the drive current flowing through the solenoid 3 and the ripple voltage with respect to the resistance value of the impedance element 7. According to the present embodiment, it can be seen that the larger the resistance value of the impedance element 7, the more the ripple voltage amplitude can be suppressed. As described above, this ripple voltage is observed as a voltage corresponding to the wiring impedance from the DC power supply 2 and the voltage dividing ratio of the impedance element 7. Therefore, it can be seen that the larger the value of the impedance element 7 is, the larger the voltage division ratio becomes, so that the ripple voltage becomes smaller.

  On the other hand, FIG. 6 shows the relationship between the drive current of the solenoid 3 and the loss of the impedance element 7 with respect to the resistance value of the impedance element 7. According to the present embodiment, it can be seen that the greater the resistance value of the impedance element 7, the greater the loss. Since the loss is caused by the impedance element 7 and the current flowing therethrough, it can be understood that if the solenoid current is the same, the loss is proportional to the resistance value of the impedance element 7.

  As described above, the ripple voltage and the loss of the impedance element 7 are in a contradictory relationship. That is, from the viewpoint of reducing conduction noise, it is desirable to increase the resistance of the impedance element 7, but from the viewpoint of loss, it is desirable to decrease the resistance of the impedance element 7. Therefore, the range of the value of the impedance element 7 is naturally determined from the allowable range of the ripple voltage and the allowable range of the loss of the impedance element 7. For example, when the maximum ripple voltage is 0.4 V or less and the loss of the impedance element is allowed up to 0.7 W, the resistance value of 6Ω is selected, and the maximum ripple voltage is 1.4 V or less and the loss of the impedance element is 0. If up to 4W is allowed, 2Ω should be selected.

  As described above, the resistance value of the impedance element 7 may be appropriately selected from the relationship between the ripple voltage and the loss according to the specification of the drive control device of the applied electromagnetic coil, and in short, the conduction noise is efficiently reduced. In addition, a resistance value that can reduce loss can be selected.

  Here, the impedance element 7 has been described as a resistor. However, as shown in FIGS. 7A to 7F, a passive element other than a resistor, an active element, or a combination with a resistor may be used. A specific configuration of the impedance element 7 will be described with reference to FIGS. 7A to 7F. 7A to 7F propose a configuration in which a resistor is used as a basic configuration and other impedance elements are combined with this in order to efficiently reduce noise.

  FIG. 7A shows an example in which a single resistor is used as the impedance element 7. By using a single resistor, it is possible to reduce the circuit mounting area and to reduce the cost.

  FIG. 7B shows an example in which two resistors are used in parallel as the impedance element 7. The loss of the impedance element 7 is proportional to the square of the flowing current. Therefore, by dispersing the resistor Ra and the resistor Rb, it is effective to reduce the loss of each resistor by half.

  FIG. 7C shows an example of a plurality of (here, two) resistors and a plurality of resistance adjusting elements for selecting them, that is, switching elements, as the impedance element 7. In this example, the case where two each is arrange | positioned is shown. The resistor Rx and the resistor Ry desirably have different resistance values. By doing so, a plurality of selections can be made by a combination of ON / OFF of the switch SWx and the switch SWy. For example, if one resistance value is increased and the other resistance value is decreased, conduction noise can be further suppressed when one resistance value is selected, and loss is further reduced when the other resistance value is selected. be able to.

  FIG. 7D shows an example in which a resistor is connected in parallel between the collector and emitter of a bipolar transistor TR having a function of a resistance adjusting element as the impedance element 7. When the on-resistance between the collector and the emitter is changed by controlling the base current of the bipolar transistor TR, a parallel resistance with the resistor R can be formed, so that the resistance value can be changed steplessly. As a result, there is an effect that conduction noise is suppressed and loss can be appropriately selected. Further, when the bipolar transistor TR fails in an off state, the resistor R can be used independently, and therefore a fail-safe function is provided.

  FIG. 7E shows an example in which a resistor R and an inductance L are combined in series as the impedance element 7. This is effective when it is desired to further increase the impedance of the frequency in the high frequency band, that is, to further suppress high-frequency conduction noise.

  FIG. 7F shows an example in which a parallel resonant circuit of a resistor R, an inductance L, and a capacitor C is used as the impedance element 7 in series. This is effective when it is desired to increase impedance at a specific frequency, that is, to suppress specific conduction noise more.

  When the impedance element 7 as shown in FIGS. 7E and 7F is used, it is extremely easy to appropriately combine a resistor, an inductance, and a capacitor. An inductance or a capacitor is suitable as an impedance element because there is no loss.

  As described above, according to the first embodiment, the impedance element 7 and the capacitor 6 are connected from the positive line L1 to the negative line L5 to the connection line L3 connecting the positive line L1 and the negative line L5 of the DC power supply. Are connected in series through a free-wheeling diode so that a free wheel current flows through the impedance element 7 and the capacitor 6, and the free-wheeling current 5 is connected to the impedance element 7 and the capacitor 6. The anode side and one end of the solenoid 3 and the negative electrode line L3 are connected by a low-side switching element 4.

  According to this configuration, the conduction noise caused by the drive current of the solenoid 3 can be suppressed by the impedance element 7, and the capacitance of the capacitor 6 can be further reduced. Therefore, the drive control device for the electromagnetic coil can be downsized. Is.

  Next, a second embodiment of the present invention will be described in detail with reference to FIGS. The second embodiment uses two solenoids 3 and shows, for example, an electromagnetic coil of a hydraulic control valve used for each of an intake valve and an exhaust valve used in a valve timing control device.

  The embodiment shown in FIG. 8 is characterized in that two drive circuits shown in FIG. 1 are provided and the impedance element 7 and the capacitor 6 are connected to the two drive circuits in common. Since the functions of the impedance element 7 and the capacitor 6 are substantially the same as those of the impedance element 7 and the capacitor 6 shown in FIG. 1, detailed description thereof will be omitted and the circuit configuration will be described.

  One drive circuit includes a solenoid 3a, a connection line L2a, a switching element 4a, and a return diode 5a, and the other drive circuit includes a solenoid 3n, a connection line L2n, a switching element 4n, and a return diode 5n. These basic connections are substantially the same as the circuit shown in FIG. The cathodes of the free-wheeling diode 5a and the free-wheeling diode 5n are connected to a connection line L3 between the impedance element 7 and the capacitor 6. According to this configuration, only one impedance element 7 and one capacitor 6 are required, which is effective in reducing the number of components. In this case, it is necessary that the capacitance of the capacitor 6 and the resistance value of the impedance element 7 be adapted to values according to the two drive circuits.

  The embodiment shown in FIG. 9 shows a modification of the embodiment shown in FIG. 8, and includes two drive circuits shown in FIG. 1, and an impedance element and a capacitor are also provided in each drive circuit correspondingly. It is what. Also in this embodiment, the functions of the impedance element 7 and the capacitor 6 are substantially the same as those of the impedance element 7 and the capacitor 6 shown in FIG.

  One drive circuit includes a solenoid 3a, a connection line L2a, a switching element 4a, and a return diode 5a, and the other drive circuit includes a solenoid 3n, a connection line L2n, a switching element 4n, and a return diode 5n. The cathode of the return diode 5a is connected to the line L3a together with the impedance element 7a and the capacitor 6a, and the cathode of the return diode 5n is connected to the line L3n together with the impedance element 7n and the capacitor 6n. These basic connections are substantially the same as the circuit shown in FIG.

    According to this embodiment, since the impedance elements 7a and 7n and the capacitors 6a and 6n exist independently in each of the two drive circuits, it is particularly effective for reducing the loss of the impedance element 7. In the embodiment of FIG. 8, since the impedance element 7 is commonly used for the two drive circuits, the resistance value thereof increases, and there is a possibility that the loss increases as shown in FIG. However, in the embodiment shown in FIG. 9, since the impedance elements 7a and 7n are provided in the respective drive circuits, the resistance value can be reduced, so that the loss can be reduced. Although the impedance element 7 has been described as a resistor, an impedance element having a configuration as shown in FIGS. 7A to 7F can also be used.

  As described above, according to the second embodiment shown in FIGS. 8 and 9, since the capacitor 6 and the impedance element 7 can be arranged even in the drive circuit of the plurality of solenoids 3, the conduction noise is reduced. By reducing the capacitance of the capacitor, the size of the electromagnetic coil drive control device can be reduced.

  Hereinafter, the loss reduction method of the impedance element in the configuration of the second embodiment will be described.

  The loss of the impedance element 7n in the configuration having the two drive circuits shown in the embodiment of FIG. 8 will be described with reference to FIGS. The analysis waveform and average loss by the circuit analysis tool are shown.

  FIG. 10 shows the timing at which the two drive circuits change simultaneously. In FIG. 10, when the switching element 4a and the switching element 4n of the two drive circuits are turned off (illustration: circuit 1 off, circuit 2 off), the freewheeling diode 5a and the freewheeling diode 5n are forward biased (circuit 1 current (reflux)). , Circuit 2 current (reflux)), the solenoid current recirculates (illustration: solenoid current 1, solenoid current 2), and the voltage across the capacitor 6 increases with time (illustration: voltage across the capacitor). Therefore, it can be seen that the current flowing through the impedance element 7n also rises and the point at which the switching element transitions from OFF to ON becomes the maximum current (illustration: impedance element current). Since the solenoid current from the two drive circuits circulates in the impedance element 7n, the current is about twice as large, and the loss increases from the square of R × I to about four times that in the case of one drive circuit. . According to the analysis result, it can be seen that the average loss is as large as about 1160 mW (illustration: impedance element loss).

  FIG. 11 shows a case where the phases of PWM drive of the two drive circuits are shifted by a half cycle. When the switching element 4n is turned off (illustration: circuit 2 off), the freewheeling diode 5n is forward biased and the solenoid current recirculates (illustration: solenoid 2 current). On the other hand, the switching element 4a is in an on state (illustration: circuit 1 is on), the freewheeling diode 5n is reverse-biased and does not recirculate (illustration: solenoid 1 current). Thus, since one of the two drive circuits does not recirculate (illustration: no circuit 1 recirculation, circuit 2 recirculation), the current flowing through the impedance element 7n can be reduced (illustration: impedance element current). According to the analysis result, it can be seen that the average loss is suppressed to about 910 mW (illustration: impedance element loss).

  Further, according to the VB ripple voltage shown in FIG. 10 (illustration: ripple voltage) and the VB ripple voltage shown in FIG. 11 (illustration: ripple voltage), the VB ripple voltage is greatly increased by shifting the PWM phase. The effect that it can be reduced can be seen.

  The loss of the impedance elements 7a and 7n in the configuration having the two drive circuits shown in the embodiment of FIG. 9 will be described with reference to FIGS. The analysis waveform and average loss by the circuit analysis tool are shown.

FIG. 15 shows the timing at which the two drive circuits change simultaneously. In FIG. 15, when the switching element 4a of the two drive circuits is turned off (illustration: circuit 1 off), the freewheeling diode 5a becomes forward biased, the solenoid current recirculates (illustration: solenoid 1 current), and both ends of the capacitor 6a. The voltage rises with time (illustration: voltage across the capacitor). It can be seen that the current flowing through the impedance element 7a also increases (illustration: impedance element current), and the point at which the switching element transitions from OFF to ON is the maximum current.
When the switching element 4n is turned off (illustration: circuit 2 off), the freewheeling diode 5n becomes forward biased, the solenoid current recirculates (illustration: solenoid 2 current), and the voltage across the capacitor 6n increases with time. (Figure: Voltage across capacitor). Then, it can be seen that the current flowing through the impedance element 7n also increases (illustration: impedance element current), and the point at which the switching element transitions from OFF to ON is the maximum current. According to the result of the analysis tool, it can be seen that the average loss is about 330 mW (illustration: impedance element loss).

FIG. 16 shows a case where the phases of PWM drive of the two drive circuits are shifted by a half cycle. When the switching element 4n is turned off (illustration: circuit 2 off), the freewheeling diode 5n is forward biased and the solenoid current recirculates (illustration: solenoid 2 current). On the other hand, the switching element 4a is in an on state (illustration: circuit 1 is on), the freewheeling diode 5n is reverse-biased and does not recirculate (illustration: solenoid 1 current). As described above, it can be seen that the point at which the switching element transitions from off to on is the maximum current (illustration: impedance element current). According to the result of the analysis tool, it can be seen that the average loss is 320 mW (illustration: impedance element loss).
In this way, since the two drive circuits are arranged with impedance elements in each of them, the currents of the two are not combined, so that the loss does not increase.

  From the above two forms, in order to improve the loss when the impedance element is shared, the method of shifting the timing at the peak of the current leads to lowering the average current, and it is possible to obtain a large loss reduction effect. It is obvious.

  Furthermore, according to the VB ripple voltage (illustrated: ripple voltage) shown in FIG. 15 and the VB ripple voltage (illustrated: ripple voltage) shown in FIG. 16, the VB ripple voltage is also greatly reduced by shifting the phase of the PWM. You can see the effect of being able to do it.

  Next, a control method in a configuration having two drive circuits shown in the second embodiment will be described. Both FIG. 12 and FIG. 13 show timing waveforms and block configurations when a timer module of a microcomputer is used, and an embodiment will be described.

FIG. 12 shows a control method in which the timing is shifted by a predetermined phase difference. FIG. 12A is a timing diagram, and FIG. 12B shows the block configuration and describes the flow of operation.
(FIG. 12A1) The initial value of the fixed-cycle timer 11a is zero. This is an up timer that receives a reference clock Clk, starts counting up one by one, and is cleared to zero every PWM cycle. Ch1 = 0 indicates that the drive circuit 1 is on, and CH2 = 1 indicates that the drive circuit 2 is off. The threshold register 12a is a PWM on-time setting value of the driving circuit 1, the threshold register 12b is a PWM on-time setting value of the driving circuit 2, and the shift value register 14 is a phase difference (timing shift) time of the driving circuit 2. A setting value, and a half cycle of the PWM frequency will be described as an example of the setting value.

  (FIG. 12A2) The output Th1 of the threshold register 12a is input to the comparator 13a and becomes higher than the output Tm1 of the fixed period timer 11a (A> B is true), Ch1 becomes 1 and the drive circuit 1 Turns off.

  (FIG. 12A3) When the value Tm1 of the fixed period timer 11a = the value Sft of the shift value register 14, Ch2 = 0 and the drive circuit 2 is turned on.

  (FIG. 12A4) When the value Tm1 of the fixed cycle timer 11a> (the value Sft of the shift value register 14 + the value Th2 of the threshold value register 12b), Ch2 of the comparator 13b becomes 1, and the drive circuit 2 is turned off.

  As described above, the control method shifts the timing by a predetermined phase difference. The phase difference has been described with a half cycle (PWM cycle / 2) when there are two drive circuits. However, when the number of drive circuits is increased, for example, three circuits are PWM cycles / 3, and four circuits are PWMs. Needless to say, the period / 4 is effective.

  FIG. 13 shows a control method in which the timing is shifted by starting the other timer using an end event of one timer as a trigger. FIG. 13A is a timing diagram, and the configuration is shown in FIG. 13B and the flow of operation will be described.

  (FIG. 13A1) The fixed-cycle timer 11a has an initial value of zero. This is an up timer that receives a reference clock Clk, starts counting up one by one, and is cleared to zero every PWM cycle. Ch1 = 0 indicates that the drive circuit 1 is on, and CH2 = 1 indicates that the drive circuit 2 is off. The threshold register 12 a is a PWM on-time setting value of the drive circuit 1, and the threshold register 12 b is a PWM on-time setting value of the drive circuit 2.

  (FIG. 13A2) The output Th1 of the threshold register 12a is input to the comparator 13a and becomes higher than the output Tm1 of the fixed-cycle timer 11a (A> B is true), Ch1 becomes 1 and the drive circuit 1 Turns off.

  At the same time, Ch2 becomes 0 and the drive circuit 2 is turned on (this time is the maximum current of the drive circuit 1 and the minimum current of the drive circuit 2). When Ch is 1, the count permission EN of the fixed-cycle timer 11b is enabled, and the reference clock Clk is input to start counting up one by one.

  (FIG. 12A3) When the value Tm2 of the fixed cycle timer 11b> the value Th2 of the threshold value register 12b, Ch2 of the comparator 13b becomes 1 and the drive circuit 2 is turned off.

  As described above, this is a control method in which the timing is shifted by starting the other timer using the end event of one timer as a trigger. In the present embodiment, it is needless to say that the sum of the ON times of the two drive circuits must not exceed the PWM period (when the number of drive circuits is increased, for example, the same applies to three circuits and four circuits). .

DESCRIPTION OF SYMBOLS 1 ... Drive control apparatus of an electromagnetic coil, 2 ... DC power supply, 3, 3a, 3n ... Electromagnetic coil (solenoid) 4, 4a, 4n ... Switching element 5, 5a, 5n ... Freewheeling diode, 6, 6a, 6n ... Capacitors 7, 7a, 7n ... impedance elements, L1 ... positive line, L2, L3, L4 ... connection line, L5 ... negative line, L2a, L2n, L3a, L3n, L4a, L4n ... connection line.
11a, 11b ... fixed-cycle timer, 12a, 12b ... threshold register,
13a, 13b ... comparator, 14 ... shift value register, 15 ... adder

Claims (6)

A first electromagnetic coil having one end connected to the positive electrode side of the DC power supply;
A first switching element connected to the other end of the first electromagnetic coil to turn on / off the current flowing through the first electromagnetic coil;
A first free-wheeling diode that recirculates the electrical energy stored in the first electromagnetic coil as a freewheel current when the first switching element is turned off;
A capacitor and an impedance element are arranged in series on a connection line connecting the positive electrode line and the negative electrode line of the DC power source, and the connection line between the capacitor and the impedance element and the other end of the first electromagnetic coil are connected to each other. Connected via the first freewheeling diode;
A second electromagnetic coil having one end connected to the positive electrode side of the DC power supply;
A second switching element connected to the other end of the second electromagnetic coil to turn on / off the current flowing through the second electromagnetic coil;
A second free-wheeling diode that recirculates the electrical energy stored in the second electromagnetic coil as a freewheel current when the second switching element is turned off;
The capacitor and the impedance element are arranged in series on a connection line connecting a positive electrode line and a negative electrode line of the DC power supply, and the connection line between the capacitor and the impedance element and the other end of the second electromagnetic coil. And via the second reflux diode,
The operation of the first switching element and the second switching element is driven by shifting the timing so that the on and on or off and off operations do not overlap at the same time. apparatus. A first electromagnetic coil having one end connected to the positive electrode side of the DC power supply;
A first switching element connected to the other end of the first electromagnetic coil to turn on / off the current flowing through the first electromagnetic coil;
A first free-wheeling diode that recirculates the electrical energy stored in the first electromagnetic coil as a freewheel current when the first switching element is turned off;
A first capacitor and a first impedance element are arranged in series on a connection line connecting the positive electrode line and the negative electrode line of the DC power supply, and the connection line between the first capacitor and the first impedance element. And the other end of the first electromagnetic coil are connected via the first reflux diode,
A second electromagnetic coil having one end connected to the positive electrode side of the DC power supply;
A second switching element connected to the other end of the second electromagnetic coil to turn on / off the current flowing through the second electromagnetic coil;
A second free-wheeling diode that recirculates the electrical energy stored in the second electromagnetic coil as a freewheel current when the second switching element is turned off;
A second capacitor and a second impedance element are arranged in series on a connection line connecting the positive electrode line and the negative electrode line of the DC power supply, and the connection line between the second capacitor and the second impedance element. And the other end of the second electromagnetic coil are connected via the second reflux diode,
The operation of the first switching element and the second switching element is driven by shifting the timing so that the on and on or off and off operations do not overlap at the same time. apparatus. The drive control apparatus of the electromagnetic coil of Claim 1 WHEREIN:
Control by shifting the on / off operation timing of the first switching element and the second switching element is:
A drive control of an electromagnetic coil comprising a control method of shifting timing so that one of the first switching element and the second switching element is turned on and then the other is turned on after a predetermined phase difference. apparatus. In the drive control apparatus of the electromagnetic coil of Claim 2,
Control by shifting the on / off operation timing of the first switching element and the second switching element is:
A drive control of an electromagnetic coil comprising a control method of shifting timing so that one of the first switching element and the second switching element is turned on and then the other is turned on after a predetermined phase difference. apparatus. The drive control apparatus of the electromagnetic coil of Claim 1 WHEREIN:
Control by shifting the on / off operation timing of the first switching element and the second switching element is:
An electromagnetic coil drive control device comprising a control method of shifting timing so that one of the first switching element and the second switching element is turned off and the other is turned on. In the drive control apparatus of the electromagnetic coil of Claim 2,
Control by shifting the on / off operation timing of the first switching element and the second switching element is:
An electromagnetic coil drive control device comprising a control method of shifting timing so that one of the first switching element and the second switching element is turned off and the other is turned on.