DE102006009628A1 - Device for controlling an electromagnetic actuator - Google Patents

Abstract

at a method for controlling an electromagnetic actuator a circuit device is provided which has an input (80.2) for connection to a supply voltage (UV), an input (80.3) for connection to GND, two outputs (80.4, 80.5) for connecting a load (100), at least one switching element (10) to interrupt the power supply and a device (20) for detecting the current. A control (60) is used for measuring current and supply voltage as well as for control the at least one switching element (10). By doing that the control (60) based on current and altitude the supply voltage is the impedance of the load of the actuator calculated and necessary for the operation of the actuator power determined, valve coils are identified by their rated voltage and for the industrial use made usable.

Description

Territory of invention

The The invention relates to a device for controlling an electromagnetic Actuator such as a magnetic coil, in particular a magnetic coil at hydraulic or Pneumatic switching valves, preferably in the field of plastic injection molding machines according to the preamble of claim 1.

State of technology

In the industrial sector, hydraulic switching valves with a supply voltage of 24V _DC are traditionally used. The same applies to pneumatics in industrial applications. Prescribed by the vehicle electrical system, the supply voltages of switching valves in the mobile area are usually 12V _DC . However, the range of valves and their switching logic is comparable.

From the DE 40 31 427 A1 For example, a method and a device are known which, with the aid of pulse-width-modulated supply voltage, permit energy-reduced operation with readjusted power adaptation of an electromagnetic actuator. This method reduces the power cyclically to a minimum power (P ₀ ) and can thus reach the limit of the holding torque of the actuator. For this purpose coil current and coil voltage are measured and the power in the coil is reduced continuously or in fixed stages until the actuator moves, ie the counterinduction in the coil is detected by the coil current. This power P ₀ is provided with an offset and delivered to the coil as a minimum power. The method is independent of the connected load, with small inductive loads, the recognition of the actuator movement is difficult because of the low mutual induction by coil current and voltage. In addition, there is the danger that in critical applications under high load or with spontaneously acting disturbances, the load at least partially moves out of the desired state.

From the DE 39 10 810 A1 a circuit arrangement is known in which with an adjustable pulse width modulation (PWM) a reduced-power operation of electromagnetic actuators is realized.

epiphany the invention

outgoing From this prior art, the invention is based on the object Identify valve coils according to their rated voltage and this for the industrial use.

This Task is by a method of controlling an electromagnetic An actuator with the features of claim 1 solved.

At Hand of the current and voltage characteristics when applying the supply voltage to the actuator, the impedance can be calculated and from it closed on the actuator, which then operated accordingly becomes. Preferably, the supply voltage is at least as high like the rated voltage of the actuator.

If necessary, can be used to identify valve coils of different nominal voltages and for the industrial use at different supply voltages usable do. about an adjustment of the duty cycle within a preferably used Pulse width modulated supply can be the electromagnetic Actuators for one wide range of different supply voltages used become. The height the supply voltage is essentially only of the permissible insulation voltage limited to the coil. In operation, fluctuations in the supply voltage balanced by adjusting the duty cycle, so that the middle Coil current remains constant.

in the Starting torque increases the current in the connected inductive Load in an e-function. With the movement of the actuator, that is, the deflection of the actuator from the rest position to the active one End situation, there is a short-term interruption of the current increase, which for function monitoring can be evaluated.

By a time-limited overexcitation, i. Operating at a power which is well above the rated power of the electromagnetic Actuator is scattered, the duty cycle over various Actuators of one series and / or different operating points (for valves e.g. Pressure, flow rate, temperature, viscosity of the medium) minimized.

Further Advantages emerge from the subclaims and the following Description.

Summary the figures

in the The invention will be explained in more detail with reference to the attached figures.

It demonstrate:

1 a block diagram of a circuit according to the invention,

2 a circuit diagram of a circuit in a opposite 1 concretized embodiment,

3 - 5 Diagrams of voltage and current over time on different valve coils as a load.

description preferred embodiments

Before the invention is described in detail, it should be noted that they do not affect the respective components of the device or the explained procedure limited under the procedure is because these components and methods can vary. The ones used here Terms are just for that determined, special embodiments too describe and are not used restrictively. If in the Description and in the claims the singular or indefinite articles are used refer These also apply to the majority of these elements, if not the overall context clearly makes something else clear. The same thing applies in the opposite direction.

The The method described below is preferably applied to actuators of valves on an injection molding machine for the processing of plasticizable materials, in particular a plastic injection molding machine used.

In the drive circuit 80 according to 1 is via at least one switching element 10 a supply voltage U _V via the outputs 80.4 . 80.5 to a connected load 100 created. The circuit is via input 80.2 at the supply voltage U _V and via input 80.3 connected to GND. The switching element 10 is about a control 60 over connections 60.2 switched on or off. In addition to the switching element 10 is a current sensor 20 intended.

Is the switching element 10 closed, current flows from the supply pin 80.2 via current sensor 20 , Switching element 10 and about the connected load 100 to GND. The electromagnetic actuator turns on. The thereby flowing current is the control 60 from the current sensor 20 provided as information. In addition, the height of the supply voltage U _{V is} measured. From the two information current (here coil current) and voltage (here supply voltage) becomes the impedance of the load 100 calculated. The means for detecting current and supply voltage may be in the control 60 integrated or available externally. The current sensor 20 can also in the switching element 10 be integrated.

The decision with which power the load (coil of the electromagnetic actuator) must be operated, is in the control 60 determined based on the calculated impedance.

Detects the control 60 as a load, a coil of lower nominal voltage, the switching element 10 from the control 60 switched in clock mode and thus the power to the load of the coil fits over a pulse width modulated voltage. The duty cycle within the clock mode is also dependent on the applied supply voltage U _V. With increasing supply voltage, the duty cycle is reduced and vice versa. As a result of this adaptation, the average coil current is kept constant even when the supply voltage U _{V is} variable.

The control is a variety of different inductive loads of different nominal voltage known. The detection of the respective load takes place via the impedance of the load. The switching frequency of the pulse width modulation (PWM) is chosen so high that the inductive load acts as the storage inductor of a switching regulator. At the valve coil, a "quasi" DC current sets in with little residual ripple. Coil current and supply voltage are preferably measured in each cycle. The supply voltage U _V must be at least as high as the rated voltage of the connected load. If the supply voltage exceeds the rated voltage of the load, it is dynamically switched to cycle mode (and back again). The loads known to the actuator can thus be operated well above rated voltage (limited only by the insulation resistance of the insulation of the coil wire). The PWM is dynamically adapted to the supply voltage. Thus, with a voltage source loads of different nominal voltage can be operated.

Based of the coil current, the switching of the load can be detected and thus valve clamp, e.g. by foreign bodies. The supervision the coil current can be used as a short circuit detection, as an electronic fuse. This increases the short-circuit safety of the Actuator itself

The circuit device may have an additional control input 80.1 have, by which the switching on and off of the circuit can be controlled by itself

In the embodiment of the 2 are in the drive circuit 80 two switching elements 10 . 30 intended. Both switching elements, which are designed here as MOSFET switches, logically as normally open, are controlled by control 60 over connections 60.2 . 60.3 switched on or off. In the circuit example is in addition to the switching element 10 a current sensor 20 (here, for example, a shunt resistor) provided. With 70 an internal extinguishing element is marked.

Are both switching elements 10 . 30 CLOSED sen, current flows from the entrance 80.2 via switching element 10 , Current sensor 20 , about the connected load 100 and via switching element 30 to GND. The electromagnetic actuator turns on. The thereby flowing current is the control 60 from the current sensor 20 via the A / D converter 40 the control 60 at the entrance 60.5 provided as information. In addition, the level of the supply voltage is measured and via the A / D converter 50 for voltage measurement of the control 60 at the entrance 60.4 made available. From the two information current and voltage, as in the first embodiment, the impedance of the load 100 calculated.

The circuit works as follows. According to 3 At time t _IN1, a digital control signal is present at the input 60.1 of the control. The control closes both switching elements at the same time 10 . 30 , Thus, the voltage U _LAST (U _V - losses at the switching elements 10 . 30 as well as at the current sensor 20 ) on the connected load 100 (Spool). The coil current I _LOAD increases in an e-function until the time t ₁ . By the movement of the actuator of the actuator from the rest position towards the active end position, there is a short-term interruption of the current increase, until the time t _2, the actuator is in the end position. The current increase reaches the maximum value at time t ₃ . At time t ₃ , the control identifies the nominal power of the connected load based on the coil current and the supply voltage 100 , In the example of 3 No power adjustment via PWM is required. In addition, the inflection point occurring at the moment of time t ₂ at the time of switch-on can be used to increase the current for function monitoring of the actuator, since this inflection point occurs as a result of the movement of the actuator. In most cases, the curve of the current over time at this point is not monotonically increasing or possibly even unsteady

Is as a load according to 4 a coil of lower rated voltage is connected, after the actuator is safely in the end position, switched to the clock mode. The current and thus the effective power across the coil is reduced to the nominal value of the device to prevent thermal destruction of the coil. In this case, there is a digital control signal at the input at time t _IN2 60.1 of the control. The control closes both switching elements at the same time 10 . 30 , Thus, the voltage U _{LAST is connected} to the connected load 100 , The coil current I _LOAD increases in an e-function until the time t ₄ . By the movement of the actuator of the actuator from the rest position towards the active end position, there is also a short-term interruption of the current increase, until the time t _5, the actuator is in the end position. The current increase reaches the maximum value at time t ₆ . At time t ₆ , the control identifies the rated power of the connected load based on the coil current and the supply voltage 100 and it clocks at least one of the switching elements 10 . 30 at the times t ₇ , t ₈ . as a result, when the voltage U _{LAST is} pulsed, the coil current I _LOAD is reduced.

If the supply voltage is reduced during operation, the duty cycle will be as in 5 shown at the time t ₉ increased accordingly and the coil current remains constant, that is, when clocked voltage applies to the current I _LAST in the controlled state, regardless of the amount of supply voltage U _V : ∫I (t) dt = const.

By the overexcitation of the electromagnetic actuator, the scatters of the Duty cycle over different devices a series and / or different operating points minimized.

10 30

switching element

20

current sensor

40

A / D converter for current measurement

50

A / D converter for voltage measurement

60

control

60.1,60.4,60.5

entrance

60.2,60.3

connections

70

internal suppressor

80

drive circuit

80.1

control input

80.2,80.3

entrance

80.4,80.5

output

100

load

t _ON1

time

t ₁ , t ₂ , .., t ₁₀

time

I _LAST

coil current

U _LOAD

voltage signal

U _V

supply voltage

Claims (14)

Method for controlling an electromagnetic actuator with a circuit device, comprising: - an input ( 80.2 ) for connection to a supply voltage (UV), - an input ( 80.3 ) for connection to GND, - two outputs ( 80.4 . 80.5 ) for connecting a load ( 100 ), - at least one switching element ( 10 . 30 ) for the interruption of the power supply, - a device ( 20 ) for detecting the current, - a control ( 60 ) for measuring current and supply voltage as well as for controlling the we at least one switching element ( 10 . 30 ), characterized in that the control ( 60 ) calculated on the basis of current and the amount of supply voltage, the impedance of the load of the actuator and determines the power required for the operation of the actuator. Method according to claim 1, characterized in that the control of the at least one switching element ( 10 . 30 ) takes place under pulse width modulation. Method according to claim 1 or 2, characterized in that by means of the at least one switching element ( 10 . 30 ) is generated a pulse width modulated voltage for adjusting the power to the specific power in the connected electromagnetic actuator. Method according to one of the preceding claims, characterized in that the circuit device has an additional control input ( 80.1 ), by which the switching on and off of the circuit device can be controlled Method according to one of the preceding claims, characterized in that the device ( 20 ) for detecting current and supply voltage in the control ( 60 ) is integrated or available externally Method according to one of claims 1 to 4, characterized in that the device ( 20 ) for detecting the current in the switching element ( 10 ) is integrated Method according to one of the preceding claims, characterized in that the duty cycle of at least one of the switching elements ( 10 . 30 ), clocked voltage signal (U _LAST ) depends on the level of the supply voltage (U _V ). Method according to one of the preceding claims, characterized in that when clocked voltage for the current (I _LAST ) in the controlled state, regardless of the level of the supply voltage (U _V ) applies: ∫I (t) dt = const. Method according to one of the preceding claims, characterized in that at the turn-on (t ₂ , t ₅ ), the at least one inflection point in the increase of the current is used to monitor the operation of the actuator. Method according to one of the preceding claims, characterized in that the control element ( 60 ) a plurality of different inductive loads of different nominal voltage is known. Method according to one of the preceding claims, characterized characterized in that the switching frequency of the pulse width modulation chosen so high is that the inductive load as the storage inductor of a switching regulator acts. Method according to one of the preceding claims, characterized characterized in that coil current and supply voltage preferably be measured in every bar. Method according to one of the preceding claims, characterized in that the supply voltage (U _V ) greater than or equal to the rated voltage (U _LAST ) of the load ( 100 ). Method according to one of the preceding claims, characterized characterized in that the method on an injection molding machine for the processing of plasticizable materials, in particular a plastic injection molding machine is used.