Electricity: power supply or regulation systems – Output level responsive – Using a three or more terminal semiconductive device as the...
Reexamination Certificate
2002-09-13
2003-12-30
Berhane, Adolf D. (Department: 2838)
Electricity: power supply or regulation systems
Output level responsive
Using a three or more terminal semiconductive device as the...
C323S284000
Reexamination Certificate
active
06670797
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention pertains to a method for controlling a converter that converts the primary input voltage to a secondary output voltage. It also concerns a device for execution of the method. Converter here is understood to mean, in particular, a dc/dc converter.
This type of converter is frequently used in a so-called multivoltage network, in order to convert the primary input voltage referred to the converter to a comparatively high or low secondary output voltage. This type of multivoltage system is therefore commonly found in a vehicle as electrical power supply system, which, in addition to the low voltage loads generally set at a dc voltage of 12V, also operates with at least one heavy-duty load set, for example, at 42V. The system in the vehicle field comprises for this purpose a corresponding high-power generator and/or a corresponding heavy-duty battery, as well as a dc/dc converter that converts the dc voltage of, say, 42V to a 12V voltage of at least roughly the same power. The multivoltage network of a vehicle ordinarily also includes a low voltage battery, i.e., a 12V battery for example.
Regulation or control that adjusts the secondary output voltage of the converter in the direction toward a stipulated reference value is assigned to the common dc/dc converter within the electrical power supply system of a vehicle. A regulation or control intervention is required, in particular, when the output voltage drops as a result of power takeoff of a secondary load, especially below a stipulated threshold. When a low voltage battery is connected on the secondary side to the converter, this is engaged and the battery recharged if this is discharged below the threshold value because of the connected low voltage load. This type of electrical power supply system for a vehicle with activation or engagement of the dc/dc converter only when required is known from DE 43 10 240 A1.
This type of control of a converter with a battery connected on the secondary side can produce an uncontrolled state during malfunction. For example, a detonating gas mixture can form from chemical processes in the secondary battery if the output voltage to be set over a correspondingly long period on the secondary side surpasses a maximum value.
SUMMARY OF THE INVENTION
The underlying task of the invention is therefore to offer a method for controlling a converter in which malfunctions are reliably avoided by monitoring the regulated or controlled converter. In particular, the functional capability of monitoring itself is also to be monitorable. Moreover, a device particularly suitable for execution of the method is to be offered.
The task according to the invention is solved by a method for controlling a converter that converts a primary input voltage to a secondary output voltage, in which a voltage value derived from an actual voltage recorded on the secondary side is compared with a reference value and, on surpassing the reference value, a control signal is generated as tripping criterion for switching off the converter, in which, during a test phase, the voltage value or the reference value is manipulated so that the tripping criterion is met.
On the one hand, a threshold value monitoring occurs for this purpose by comparison of an actual voltage recorded on the secondary side with a reference voltage that essentially represents a stipulated maximum output voltage. On the other hand, threshold value monitoring itself is checked cyclically or at stipulated test intervals with respect to its functional capability, in which during the test phase either the reference value or a voltage value derived from the actual voltage recorded on the secondary side is reduced or increased so that the converter is switched off.
With such threshold value manipulation, the tripping criterion for switching off the converter is forced. On the one hand, the functional capability of threshold value monitoring can be checked by plausibility testing of the reaction of the converter to the tripping criterion, in which the actual state of the converter is queried. For this purpose the actual voltage recorded on the secondary side and/or an actual current recorded on the secondary side are used. If the recorded value satisfies the stipulated plausibility assertion, error-free function of threshold value monitoring is assumed and the test phase is terminated. Otherwise an error message occurs. In this manner, both the functional capability of the converter and the functional capability of the threshold value monitoring itself can be checked.
In order to ensure that the converter has a defined switching state during the test phase, i.e., especially during starting of the corresponding test program or test algorithm, in an advantageous modification, a test signal is initially generated to switch on the converter. The test signal can then be generated both as a function of the actual switching state of the converter and independently of it.
Since the actual voltages continuously compared in the context of threshold value monitoring are compared discretely in time to the reference value and a corresponding plausibility assertion is therefore also available during the test phase concerning falling short or surpassing of the reference value, it can be determined even at the beginning of the test phase with the corresponding plausibility query and with the test signal activated whether error-free testing of threshold value monitoring is possible. Threshold value monitoring has the actual voltage, preferably in the form of a voltage value derived from it by division, whereas the reference value expediently represents the maximum admissible output voltage.
In a particularly simple variant of the converter-control or regulation, the output voltage is set by a voltage regulator that generates a manipulated variable for the converter when the recorded actual voltage deviates from a stipulated reference voltage. In an advantageous embodiment, the voltage regulator, however, does not directly furnish the manipulated variable for the converter on the output side, but a reference current or current reference signal, which in turn drives a current control circuit subordinate to voltage regulation. This again compares the current reference signal generated by the voltage regulator with the actual current recorded on the secondary side and generates the corresponding manipulated variable for the converter during a deviation. Control of the converter therefore occurs in the manner of cascade control, which is characterized by particularly high control dynamics and control stability.
The task is solved according to the invention by a device for controlling a converter that converts a primary input voltage to a secondary output voltage, with a first regulator to set the output voltage, with a voltmeter to record the secondary actual voltage, with a switching device connected to a control input of converter for threshold value monitoring, which compares a voltage value derived from the actual voltage with a reference value and on surpassing reference value generates a control signal as tripping, criterion to switch off converter, and with a threshold value manipulator connected to switching device to raise the voltage value or lower the reference value so that the tripping criterion is met. Advantageous embodiments or objects of the dependent claims refer back to it.
The device contains, in addition to a first regulator or voltage regulator for adjustment of the output voltage, on the one hand, a safety or switching device connected to the converter on the output side for threshold value monitoring. This generates a control signal to switch off the converter if the actual voltage recorded on the secondary side by a voltmeter surpasses a reference value. On the other hand, the device contains the threshold value manipulator that is connected on the output side to an input of the switching device. The threshold value manipulator raises or lowers the voltage value during the cyclically initiated test phase. The gauge or measu
Baker & Botts L.L.P.
Berhane Adolf D.
Siemens Aktiengesellschaft
LandOfFree
Method and device for controlling a dc-dc converter does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and device for controlling a dc-dc converter, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and device for controlling a dc-dc converter will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3116908