EP3586435A1

EP3586435A1 - Standby interruption

Info

Publication number: EP3586435A1
Application number: EP18706994.3A
Authority: EP
Inventors: Anton Berghammer
Original assignee: Ebm Papst Landshut GmbH
Current assignee: Ebm Papst Landshut GmbH
Priority date: 2017-02-22
Filing date: 2018-02-19
Publication date: 2020-01-01
Also published as: WO2018153810A1; CN211481151U; DE102017103655A1

Abstract

The invention relates to a circuit (1) for producing low voltage with voltage switching between a supply voltage (VCC) on a tap (11) for the normal mode and a lower supply voltage (VCC) for a standby mode of an appliance, in which the circuit (1) is provided with a switching regulator (2) that provides a nominal voltage Uson on a connection point (10) of the circuit (1) and a Zener diode (Z1) and a transistor (T3) are connected and mounted in parallel on said connection point (10), such that the lower supply voltage (VCC) for the standby mode can be produced by controlling the transistor (T3) to short-circuit the Zener diode (Z1), such that the lower supply voltage (VCC) is applied to the tap (11) for the standby mode.

Description

Standby Shutdown

Description:

The invention relates to a method and a device for reducing the standby losses in the standby mode in the low-voltage generation, in particular in the low-voltage generation with a voltage converter. The method relates in particular to power supplies without a galvanic separation.

The term "voltage converter" here refers in particular to a down converter, but may also be any other type of converter which serves to adapt the output voltage for the device to be supplied, in particular other power supplies connected to the mains. Electric voltage transformers are nowadays used in numerous devices for supplying the main device function and any standby functions.

If this main function or a standby function in standby mode should be active permanently or for longer periods of time, the resulting energy losses in the voltage supply with a voltage converter can have a significant share of the total energy consumption of the supplied device. For electrical devices that are operated permanently, so-called small consumers, the self-consumption of the voltage converter is a significant proportion of the total consumption of the device and plays an increasing role in the purchase decision. Due to the large number of devices powered by voltage transformers, the losses of conventional voltage transformers cause considerable costs and environmental burdens which can be reduced by the methods and devices described herein. It is also known in this context that motors such. B. fan motors are used in many devices and these are operated with a low-voltage power supply and above said standby losses.

The power supply of various electrical appliances is often done, for reasons of cost, with a single voltage converter, which takes over the supply for both the normal operation of the device as well as for a possible stand-by operation. The standby mode or standby mode (also called waiting mode) is the state of a technical device in which the actual utility function is temporarily disabled or simply not needed, but can be reactivated at any time and without preparation or longer waiting times. However, for holding the standby state usually only a certain, compared to the Normal operation reduced power requirement required. Due to the great difference between the energy and power consumption of a device in these two operating states and the need to provide the full required for normal operation power as soon as possible, prevail in standby mode, the energy losses for the operation of the voltage converter that for the actual Standby function required performance regularly. There are therefore different efforts in the prior art to reduce standby losses in on-call service. A common approach to reducing standby losses is to switch between a main supply and a standby supply. In this case, the main low-voltage supply is deactivated by a microcontroller or another circuit upon detection of the standby request. In this state, only a small portion of the electronics are powered to detect the request for active operation and to re-enable the main low-voltage supply. Disadvantage of this variant is that an additional circuit part or other circuit components are necessary to ensure the supply in standby mode.

Another variant for reducing standby losses is the disconnection of the low-voltage supply from the outside. For this purpose, a higher-level control unit is given the opportunity, by means of a set and reset signal, to put the electronic unit into the sleep mode. In this case, the supply is completely disabled, so a mimiale power consumption can be achieved. It only leads the self-consumption of the switching regulator to energy losses. The disadvantage of this solution is that the higher-level control unit must make the shutdown and the activation. This control must be integrated into the concept. In addition, galvanic isolation is required in safe applications, which in turn would drive up the cost of such a solution.

From DE 10055794 A1 a concept is known in which a power circuit having a power switch of a main body of a set of the electrical apparatus connected to a first side of an AC power supply and a power transmission controller of the main body of the set is provided with a power supply second side of the AC power supply is connected to a standby power redundancy circuit in which a "power on / off" by means of a remote control is activated, the circuit receives AC power through a Reaktanzvorrichtung, receives remote control data from the remote control, a dedicated dedicated microcomputer for control of ON / OFF of the power switch by a switch driving unit connects to a first side of the AC power supply and then drives only the dedicated microcomputer in the standby state, in the event that the power switch is turned off and the Hauptkörpe r of the set is switched off.

From DE 19530594 C1, another concept, similar in concept to the concept, is provided for the following measures in the case of an electrical appliance supplied by a voltage converter: a) During operation of the device, the voltage converter on the primary side only short periods with the network or another b) the voltage converter allows in these periods in addition to the supply of a possibly required device function and the charging of a suitable energy storage, c) in the periods in which the voltage converter is disconnected from the power supply, the function (a standby function or main function) of the device is ensured by the energy removal from the energy storage and d) the voltage converter is automatically connected to the mains (or the respective power supply) as soon as the energy supply in the energy storage is running low, to charge it, or if the device function otherwise requires. In this case, however, it is disadvantageous that, as it were, the power supply unit is always disconnected from the mains, and a supply can therefore only be effected by means of the energy store and its design, as long as a network connection does not exist.

Such solutions mentioned above are based on the principle of circuit separation, so that the actual energy consumption during the standby mode, thus temporally active during the standby mode, no actual effective power reduction undergoes.

The invention is therefore an object of the invention overcome above-mentioned disadvantages and to provide a solution in which the system-specific power loss during standby operation of a low-voltage supply is significantly reduced as such and in the preferably also a safe operation of the device, such as. B. an EC motor is given.

In particular, it is an object of the present invention to provide a solution that can be used for both intrinsically safe and other circuits.

This object is achieved by the feature combination according to claim 1. A first starting point for the development of the present invention is the recognition that the losses in standby mode essentially result from the self-consumption of the switching regulator as well as the supply of the electronic components in the circuit of a low-voltage supply with switching regulator. In a circuit topology with a switching regulator, the electronics supply is provided from the VCC voltage via a linear regulator. generated voltage. The difference between these two voltages is converted into heat loss in the switching regulator and is therefore decisive for the power loss in standby mode.

A basic idea now is to provide a circuit with which it is possible to reduce the output voltage in the standby state, without generating significant additional costs. The circuit according to the invention makes it possible in a simple manner to switch over the output voltages of the low-voltage generation from a normal mode to a standby mode. According to the invention for this purpose, a circuit arrangement for low-voltage generation with a voltage switching between a supply voltage VCC at a tap for normal operation and a lower supply voltage VCC for a standby mode of a device such. For example, an EC motor is proposed, wherein the circuit arrangement is formed with a switching regulator which provides a setpoint voltage U _so n at a defined connection point of the circuit arrangement and at this connection point 10 a Zener diode and a transistor are connected and connected in parallel to one another so that the lower supply voltage VCC for the standby mode can be realized by driving the transistor T3 to short-circuit the Zener diode and thereby apply the lower supply voltage VCC for the standby mode to said voltage tap.

In an advantageous embodiment of the invention, provision is made for a supply voltage VCC to be present in the standby mode at the voltage tap, which is formed from the sum of the setpoint voltage U _SO II and the saturation voltage VUCE_SAT of the transistor T3.

In a further advantageous embodiment of the invention is provided that in normal operation at said tap a supply voltage VCC is applied, which is formed from the sum of the setpoint voltage U _S0 n and the voltage of the Zener diode ZI.

Also, it is advantageously provided that the switching regulator with a predetermined set value voltage U n_ _so _S p is formed at the feedback pin and the target voltage U _so the circuit arrangement n by the voltage at the feedback pin is achieved by means of a setpoint input of the switching regulator.

According to the invention, the o.g. Switching solution provided to use a Zener diode in the circuit path, which is bridged with a transistor. The setpoint specification of the voltage of the switching regulator takes place in an advantageous manner by the voltage at the feedback pin of the switching regulator. If this voltage exceeds a certain threshold value and thereby flows a minimum current of Ln into the feedback pin, the switching regulator stops the clocking until this threshold value is fallen below again. Furthermore, a voltage divider is provided, whereby the einzuregelnde voltage can be selectively adjusted to the Zener diode via the voltage divider. In this case, this voltage divider is designed so that a specific nominal voltage of the voltage regulator is applied to the anode terminal of the zener diode. According to the invention, it is further provided that in the active state of

Low-voltage circuit of the diode connected in parallel to the transistor is not driven, so that the transistor is in the off state. This means that the current does not flow through the transistor but through the zener diode. In order to meet the desired state of the switching regulator of a particular setpoint voltage in the circuit and at the anode terminal of the zener diode, the voltage at VCC must be a voltage higher by the value of the zener voltage of the zener diode. By contrast, in the stand-by mode of the circuit, the zener diode is short-circuited via the transistor, whereby the potential of VCC only has to be higher by the saturation voltage of the transistor VUCE_SAT than the reduced reference voltage of the switching regulator. Since the saturation voltage of the transistor is significantly lower, a lower voltage VCC is established at the voltage tap for the supply voltage VCC.

In other words, this means that the zener diode is suitable to be chosen so that the following conditions result:

Normal operation: VCC = U _s0 n + Zu

Standby mode: VCC = U _so n + VUCE_SAT where:

VCC supply voltage at the output of the circuit

Usoii defined setpoint voltage of the voltage regulator

U _z breakdown voltage of the Zener diode

VUCE_SAT saturation voltage of the transistor.

According to the invention, the switching can be performed by a microcontroller as soon as the request for the standby mode takes place via the microcontroller interface.

Another aspect of the present invention relates to the safe state of the device, preferably an EC motor by saving a separate circuit part. In conventional circuit arrangements, shutdown paths are provided for this purpose, which enable the safety controller to put the motor in a safe state.

For this purpose, in known solutions, a separate circuit is used, which switch off the supply voltage of the motor bridge driver and thereby safely prevent the further flow of current through the motor.

According to the invention this is now solved as follows. When the supply voltage VCC of the low-voltage generation provided at the output of the circuit is switched to the lower value VCC = Usoll + ZU, an undervoltage detection of the provided bridge drivers reacts and deactivates the activation of the power transistors in the H-bridge circuit.

For this purpose, it is only necessary to ensure that such driver components of the bridge circuit are selected, which can be operated at the lower voltage VCC = Usoii + Too sure regarding the switch-off condition. However, driver modules also exist in which this reduced voltage range represents an impermissible operating state. For these, the circuit used must be extended by a transistor that can switch the supply voltage of the driver to 0V. With the two concepts, if the driver components of the H-bridge circuit are functioning correctly, the safe state of the circuit or of the device would have already been achieved.

Furthermore, according to the normative specification, however, an error of the driver components should also be assumed in principle, so that the above-mentioned o. G. safe condition could only be achieved with correct function.

In the reduced-supply voltage concept, in the event of a fault, however, the power transistors of the bridge circuit would only be driven with the reduced voltage VCC = U _so n + Zu. Since the power transistors are in the saturation region at this voltage, a high power loss is implemented in the transistor, which specifically leads to the destruction of the transistor and thus in turn to a safe state. The destruction of the transistor would have to be tolerated here, since in any case this case would be incorrect. lerhafte driver blocks would be present.

In the second case, in which the supply voltage of the driver components is additionally switched to 0V, the bridge transistors can not be driven in principle because at 0V no current flow through the transistor is possible.

If the malfunction of a bridge driver and the circuit described here is taken as a further error case, ultimately no dangerous voltage state of the supplied device or EC motor can arise, provided the control lines are assumed to be safe signals. Such an assumption is permissible in a case where, as further proposed herein, the drive signals of the driver chips are set to low levels by a circuit to be considered safe with respect to the normative requirements.

In this case, no drive signal is forwarded to the power transistors by a correctly functioning second driver module, so that the safe state is ensured.

It should be noted that, depending on the driver block used, the corresponding variant is also selected, since the other one represents an impermissible operating mode in which damage can occur during operation.

Consequently, with the circuit according to the invention not only a more efficient, but also a safer operation can be provided.

Other advantageous developments of the invention are characterized in the subclaims or will be described in more detail below together with the description of the preferred embodiment of the invention with reference to FIGS. Show it:

Fig. 1 shows an embodiment of an electrical circuit for

Low-voltage generation with a voltage switching of a supply voltage between a normal operation and a standby mode

Fig. 1a shows an alternative embodiment of an electrical circuit for low-voltage generation and

Fig. 2 shows a circuit arrangement of a bridge control.

In the following, the invention will be explained in more detail with reference to an exemplary embodiment, wherein the same reference numbers refer to the same structural and / or functional features.

FIG. 1 shows an exemplary embodiment of an electrical circuit arrangement 1 for low-voltage generation with a voltage changeover of a supply voltage VCC between a normal mode and a standby mode.

The circuit arrangement 1 is formed with a switching regulator 2 (here also marked IC1) with a predetermined setpoint voltage U _SO II_SP in order to provide a supply voltage VCC of 15V DC at the output and indeed at the tap 11, the circuit arrangement 1 for normal operation.

The switching regulator 2 also has the connections BPA CC, S and D, as well as the feedback pin FB. Terminal D serves as input for an input voltage. In the present embodiment, the switching regulator 2 is designed as a down converter and converts the input voltage of 325 V into an output voltage in the normal operation of 15V.

At tap 11, this supply voltage VCC of 15V DC for the Normal operation ready. In the circuit arrangement 1, by means of the parallel connection of the zener diode Z1 and the transistor T3, a voltage changeover from the supply voltage VCC = 15V in normal operation to a voltage of 5.3 V in the standby mode at the tap 11 can be realized.

For this purpose, the feedback pin FP is connected via a voltage divider comprising the resistors R1 / R2 to the anode terminal A of the Zener diode Z1.

Furthermore, the anode terminal Z1 and the cathode terminal of the Zener diode Z1 of the transistor T3 are connected in parallel to the anode terminal A, while the gate G of the transistor is driven by a transistor T1 via a standby control signal.

The switching regulator 2 has a fixed desired value specification for the feedback pin FB in the amount of U _SO II_SP = 1.65 V, which is effected by the voltage at the feedback pin FB. If the voltage at the feedback pin FB exceeds the setpoint voltage U _S0 H_SP of 1.65V, a minimum current of 49μΑ flows into the feedback pin and the switching controller 2 interrupts the cycle.

By the voltage divider 7 from the resistors R1, R2, the voltage of the switching regulator 2 can be adjusted accordingly. The voltage divider 7 is in the present case designed so that the resistance R1 = 3.6 kOhm and the resistance R2 of 2.0 kohms, so that sets a desired voltage of 5V at the point 10 of the circuit arrangement.

In normal operation, the transistor T3 is not activated. Thus, the current must flow through the Zener diode Z1 in normal operation. In order to realize the desired state of the switching regulator of Usoii = 5V at the point 10 of the circuit arrangement 1, the voltage VCC at the tap 11 must have a higher potential by the value of the zener voltage Uz of the zener diode Z1, which in the present case must be 10 V in total the desired 15V as supply voltage VCC at the tap 11 to realize. As such, a 10V zener diode is used in the present embodiment.

In the standby mode in which the high supply voltage of 15V is not required, the Zener diode Z1 is short-circuited via the transistor T3 by the gate G of the transistor T3 is driven. Since the voltage at point 10 of the circuit is 5V and the voltage at tap 11 is now increased only by the voltage value of the saturation voltage VUCE_SAT of 0.3V of transistor T3, the voltage VCC at attack 11 is now 5.3V. Thus, the reduced supply voltage in standby mode is about 35% of the supply voltage in normal operation. As a result, a power reduction in the exemplary embodiment with a circuit topology according to FIG. 1 is achieved from approximately 650 mW to approximately 150 mW in standby mode. FIG. 1 a shows an alternative circuit with respect to FIG. 1, in which an additional transistor T 2 is connected at point 10 of the circuit arrangement 1. Depending on the bridge driver used, the power supply of the bridge driver is additionally lowered to 0V as intended. This concerns the safety concept described, to which end the additional transistor T2 in the illustrated circuit topology is used.

FIG. 2 shows a bridge circuit 20, namely an H-bridge circuit. The bridge circuit 20 is supplied by the previously explained supply voltage VCC. The bridge circuit 20 has two driver chips IC5 and IC6, as well as four power transistors T | _ in the bridge. To the driver chips IC5 and IC6 respectively lead control lines 21, 22 to the terminals HIN and LIN. Furthermore, the driver blocks on the terminals GND, VCC, VB, HO, VS and LO. When the output voltage of the low-voltage generation is switched to 5.3 V, the undervoltage detection of the bridge drivers IC5 and IC6 responds and deactivates the driving of the power transistors TL.

If the driver components IC5, IC6 function incorrectly, the power transistors T _L are activated with the reduced supply voltage VCC of 5.3V. Since the power transistors TL are in the saturation region at this voltage, a high power loss is implemented in the respective power transistors TL, which leads to the destruction of the power transistor TL and thus ultimately to a safe state. The invention is not limited in its execution to the preferred embodiments specified above , Rather, a number of variants is conceivable, which makes use of the illustrated solution even with fundamentally different types of use.

Claims

claims

Circuit arrangement (1) for low-voltage generation with a voltage changeover between a supply voltage (VCC) at a tap (11) for normal operation and a lower supply voltage (VCC) for a standby mode of a device, wherein the circuit arrangement (1) with a switching regulator (2) is formed, which at a connection point (10) of the circuit arrangement (1) already sets a target voltage U _SO II and at this Versbindungspunkt (10) a Zener diode (Z1) and a transistor (T3) connected and indeed connected in parallel, so that the lower supply voltage (VCC) for the standby mode can be realized by driving the transistor (T3) to short-circuit the Zener diode (Z1) so that the lower supply voltage (VCC) for the standby mode is applied to the tap (11) ,

Circuit arrangement (1) according to claim 1, characterized in that in the standby mode at the tap (1) a supply voltage (VCC) is applied, which is formed from the sum of the setpoint voltage U _so n and the saturation voltage VUCE_SAT of the transistor (T3).

Circuit arrangement (1) according to claim 1 or 2, characterized in that in normal operation at the tap (1) a supply voltage (VCC) is applied, which is formed from the sum of the setpoint voltage U _S oii and the voltage of the Zener diode (Z1).

Circuit arrangement (1) according to claim 1, 2 or 3, characterized in that in normal operation, the transistor (T3) is not driven and is therefore not in the forward position. Circuit arrangement (1) according to one of the preceding claims, characterized in that the switching regulator (2) with a predetermined setpoint voltage U _SO II_SP at the feedback pin (FB) is formed and the setpoint voltage U _so n by the voltage at the feedback pin (FB ) is achieved by means of a setpoint specification of the switching regulator (2).

Circuit arrangement (1) according to claim 5, characterized in that when the setpoint voltage U _S0 H_SP at the feedback pin (FB) exceeds a defined current flows through the feedback pin (FB) and the clocking of the switching regulator (2) is interrupted until the voltage value has fallen below again.

Circuit arrangement (1) according to one of the preceding claims, characterized in that the supply voltage (VCC) at the tap (11) in the standby mode is about 30% - 35% of the value in normal operation.

Circuit arrangement (1) according to one of the preceding claims, characterized in that the gate (G) of the transistor (T3) is connected to a transistor (T1), so that by driving the transistor (T1) with a standby signal the transistor ( T3) can be controlled to bring the circuit arrangement (1) in the standby mode.

Circuit arrangement (1) according to one of the preceding claims, characterized in that further comprises a microcontroller is provided to perform the switching process from the supply voltage in normal operation to the standby mode and vice versa.