DE102017103655A1 - Standby Shutdown - Google Patents

Abstract

The invention relates to a circuit arrangement (1) for low voltage generation with a voltage switching between a supply voltage (VCC) at a tap (11) for normal operation and a supply voltage lower thereto (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) a target voltage V _set already provides and on that Versbindungspunkt (10) a Zener diode (Z1) and a transistor (T3) are connected and that connected in parallel to each other in 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 at the tap (11 ) is present.

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 isolation.

The term "voltage converter" here refers in particular to a down converter, but may also include any other type of converter which serves to adapt the output voltage for the device to be supplied, in particular power supply units which are connected to the network. 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 any standby operation. The standby mode or standby mode (also called waiting mode) is that state of a technical device in which the actual utility function is temporarily deactivated 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 is required. Due to the great difference in the energy and power consumption of a device in these two operating states and the need to provide the full required for normal operation performance as soon as possible, outweigh the energy losses for the operation of the voltage converter in standby mode 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, in safe applications a galvanic isolation is required, which in turn would drive the cost of such a solution in the air.

From the 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 set main body connected to a second side of the AC power supply is with a standby power redundancy circuit in which a "power on / off" is activated by means of a remote control, the circuit receives alternating current through a reactance device, receives remote control data from the remote control, a dedicated microcomputer for controlling on / off of the Power switch by a switch drive unit with connects 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 main body of the set is turned off.

From the DE 19530594 C1 is another, but similar idea from the idea to provide the following measures in an electrical device supplied by a voltage converter: a) during operation of the device, the voltage converter primary side only short periods of time connected to the network or other electrical supply, b ) The voltage converter allows in these periods in addition to the supply of a possibly required device function, 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 ensured by the removal of energy 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 this, 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 standby operation, does not experience an actual effective power reduction.

The invention is therefore based on the object to overcome said disadvantages and to provide a solution in which the system-specific power loss during standby operation of a low-voltage supply as such is significantly reduced and in the preferably also safe operation of the device, such. 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 voltage is generated from the VCC voltage via a linear regulator. 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. Example, proposed an EC motor, wherein the circuit arrangement is formed with a switching regulator, which provides a target voltage U _is ready at a defined connection point of the circuit and at this Versbindungspunkt 10 a Zener diode and a transistor 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 and thereby applying the lower supply voltage VCC for the standby mode to the 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 _soll and the saturation voltage V _{UCE_SAT of} the transistor T3.

In a further advantageous embodiment of the invention, it is provided that in normal operation to said tap a supply voltage VCC is applied, which is formed from the sum of the setpoint voltage U _soll and the voltage of the Zener diode Z1.

It is also provided with advantage that the switching regulator is formed with a predetermined setpoint _voltage U _{soll_SP} at its feedback pin and the setpoint voltage U _{soll of} the circuit _arrangement is achieved by the voltage at the feedback pin by means of a setpoint input of the switching regulator.

According to the invention, a zener diode is used in the circuit path to bridge the above-mentioned switching solution, which is bridged by 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 1 _min into the feedback pin, the switching controller 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 the low-voltage circuit, the transistor connected in parallel with the Zener diode 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 specific 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 standby 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 V _{UCE_SAT} than the reduced setpoint 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.

• Normalbetrieb: $$\text{VCC}={\text{U}}_{\text{soll}}+{\text{Z}}_{\text{U}}$$
  
• Bereitschaftsbetrieb: $$\text{VCC}={\text{U}}_{\text{soll}}+{\text{V}}_{\text{UCE\_SAT}}$$
  

wobei darin bedeuten:

VCC

Versorgungsspannung am Ausgang der Schaltung

U_soll

definierte Sollwertspannung des Spannungsreglers

Uz

Durchbruchspannung der Zenerdiode

V_{UCE_SAT}

Sättigungsspannung des Transistors.

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

• Normal operation: $$\text{VCC}={\text{U}}_{\text{should}}+{\text{Z}}_{\text{U}}$$
  
• Standby: $$\text{VCC}={\text{U}}_{\text{should}}+{\text{V}}_{\text{UCE\_SAT}}$$
  

where:

VCC

Supply voltage at the output of the circuit

U _shall

defined setpoint voltage of the voltage regulator

Uz

Breakdown voltage of the Zener diode

V _{UCE_SAT}

Saturation voltage of the transistor.

According to the invention, the switchover 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 reliably prevent the further current flow 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 driving of the power transistors in the H-bridge circuit.

For this purpose, it is merely necessary to ensure that such driver components of the bridge circuit are selected, which can be operated at the lower voltage V CC = U _soll + zu sicher concerning 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 case of a fault, the power transistors of the bridge circuit would only be driven with the reduced voltage VCC = U _soll + Z _U in the case of a reduced supply voltage concept. 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 be here to take into account, as would be in any case for this case faulty driver chips.

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 are shown in more detail below together with the description of the preferred embodiment of the invention with reference to FIGS.

• 1 ein Ausführungsbeispiel einer elektrischen Schaltung zur Niederspannungserzeugung mit einer Spannungsumschaltung einer Versorgungsspannung zwischen einem Normalbetrieb und einem Bereitschaftsbetrieb
• 1a ein alternatives Ausführungsbeispiel einer elektrischen Schaltung zur Niederspannungserzeugung und
• 2 eine Schaltungsanordnung einer Brückensteuerung.

Show it:

• 1 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
• 1a an alternative embodiment of an electrical circuit for low-voltage generation and
• 2 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.

In the 1 is an embodiment of an electrical circuit arrangement 1 for low voltage generation with voltage switching of a supply voltage VCC between a normal mode and a standby mode.

The circuit arrangement 1 is with a switching regulator 2 (here also marked with IC1) with a predetermined setpoint _voltage U _{soll_SP} formed to a supply voltage VCC of 15V DC at the output and that at the tap 11 , the circuit arrangement 1 ready for normal operation.

The switching regulator 2 also has the terminals BP / VCC, S and D, and the feedback pin FB. Terminal D serves as input for an input voltage. In the present embodiment, the switching regulator 2 designed as a buck converter and converts the input voltage of 325 V into an output voltage in normal operation of 15V.

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

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

The switching regulator 2 has a fixed setpoint _{specification} for the feedback pin FB in the amount of U _{soll_SP} = 1.65V, which is done by the voltage at the feedback pin FB. Exceeds the Voltage at the feedback pin FB the setpoint voltage U _{soll_SP} of 1.65V, thereby flows a minimum current of 49μA in the feedback pin and the switching regulator 2 interrupts the beats.

Through the voltage divider 7 From the resistors R1, R2, the voltage of the switching regulator 2 be adjusted accordingly. The voltage divider 7 is here designed so that the resistance R1 = 3.6 kOhm and the resistance R2 of 2.0 kOhm, so that at the point 10 the circuit arrangement sets a desired voltage of 5V.

In normal operation, the transistor T3 is not activated. Thus, the current must flow through the Zener diode Z1 in normal operation. To the nominal state of the switching regulator of U _soll = 5V at the point 10 the circuit arrangement 1 To realize, the voltage VCC has to tap 11 a potential higher by the value of the zener voltage U _{Z of} the zener diode Z1, which in the present case must be 10 V, in order to achieve the desired 15V in total as the 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. Because the tension at the point 10 the circuit 5V is and the voltage at the tap 11 now only by the voltage _value of the saturation voltage V _{UCE_SAT} of 0.3 V of the transistor T3 is increased, the voltage VCC is at the attack 11 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 embodiment with a circuit topology according to 1 from about 650mW to about 150mW in standby mode.

In the 1a is an alternative circuit over the 1 shown in which an additional transistor T2 at the point 10 the circuit arrangement 1 connected is. 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.

In the 2 is a bridge circuit 20 namely an H-bridge circuit shown. The bridge circuit 20 is supplied by the previously explained supply voltage VCC. The bridge circuit 20 has two driver chips IC5 and IC6, and four power transistors T _L 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.

If the output voltage of the low-voltage generation is switched to 5.3 V, the undervoltage detection of the bridge drivers IC5 and IC6 reacts and deactivates the activation of the power transistors T _L.

If the driver components IC5, IC6 function incorrectly, the power transistors T _{L are driven} with the reduced supply voltage VCC of 5.3V. Since the power transistors T _{L are} in the saturation region at this voltage, a high power loss in the respective power transistors T _{L is} converted, which leads to the destruction of the power transistor T _L and thus ultimately to a safe state

The invention is not limited in its execution to the above-mentioned preferred embodiments. Rather, a number of variants is conceivable, which makes use of the illustrated solution even with fundamentally different types of use.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 10055794 A1 [0008]
• DE 19530594 C1 [0009]

Claims (9)

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) a target voltage U _is already set and at this Versbindungspunkt (10) a Zener diode (Z1) and a transistor (T3) are connected and indeed connected in parallel, so that the lower supply voltage (VCC) for standby operation is realized in that the transistor (T3) is driven to close the Zener diode (Z1) short, so that the lower supply voltage (VCC) for the standby mode at the tap (11) is applied. Circuit arrangement (1) according to Claim 1 , characterized in that in the standby mode at the tap (11) a supply voltage (VCC) is applied, which is formed from the sum of the setpoint voltage U _soll and the saturation voltage V _{UCE_SAT of} the transistor (T3). Circuit arrangement (1) according to Claim 1 or 2 , characterized in that in normal operation at the tap (11) a supply voltage (VCC) is applied, which is formed from the sum of the setpoint voltage U _soll 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 passage position. Circuit arrangement (1) according to one of the preceding claims, characterized in that the switching regulator (2) with a predetermined set-point voltage U _{soll_SP} at the feedback pin (FB) is formed and the target voltage V _set by the voltage at the feedback pin (FB) by means of a setpoint specification of the switching regulator (2) is achieved. Circuit arrangement (1) according to Claim 5 , characterized in that when the setpoint _voltage U _{soll_SP} on the feedback pin (FB) _exceeds a defined current through the feedback pin (FB) flows and the clocking of the switching regulator (2) is interrupted until the voltage is 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.

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