DE102006006960A1 - Electronic device operating method, involves using pulse width modulated frequency in time period and using another pulse width modulated frequency in other time period, where time periods follow one another in recurring succession - Google Patents

Abstract

The method involves using a PWM (pulse width modulated)-frequency in a time period and using another PWM-frequency in the other time period and the latter differs from the former. The time periods follow one another in recurring succession. The time periods are smaller than a thermal time constant of a layer or component of a power semiconductor switch of the power electronics. An independent claim is included for electronic device consists of pulse width modulated operating power electronics.

Description

From the DE 102 48 375 C2 a method for current detection in converters is known. The current values recorded in the rhythm of the pulse width modulation frequency, that is to say the PWM frequency, are used to regulate the rotational speed and / or the torque of the electric motor supplied by the converter.

From the 5 to 9 It is clear that a current value can be detected per PWM period. It is also sufficient in some applications to detect only one current value per every second, third or fourth PWM period.

The The duration of the PWM period is only an integer for some inverters Multiple of a basic period executable. For example, software or hardware-dependent set a timer with this basic period, on which the entire software and the current registration aligns.

Of the The invention is therefore based on the object, a lower and / or more pleasant noise emission to reach at electrical appliances.

According to the invention Task in the method according to claim 1 and in the electrical device according to the achieved in claim 8 or 14 specified characteristics.

Important features of the invention in the method are that it is provided for operating an electrical appliance, wherein this comprises pulse-width-modulated power electronics,
wherein a first PWM frequency is used in a first time period and in a second time period a second PWM frequency different from the first one is used.

From The advantage here is that the noise emission less and more comfortable than using only one frequency. The time periods are dimensioned such that the switching losses the power semiconductor switch still remain low.

at an advantageous embodiment are in further periods used additional PWM frequencies become. The advantage here is that the noise emission is even more pleasant is.

at According to an advantageous embodiment, the time periods follow one another in a repetitive sequence. The advantage here is that only within the time periods oscillations natural oscillations of Components can build. Through a swift Alternating only small amplitudes in the natural oscillations or vibrations of device components reached.

at In an advantageous embodiment, the time periods are less than a thermal time constant of a layer or component of a Power semiconductor switch of power electronics. Advantageous is that the temperature changes only slightly when changing the PWM frequencies. Consequently is the change the mechanical stresses between sections of the power semiconductor, such as Semiconductor layers, bonds, housings and the like, each other low and thus the life of the device high.

at According to an advantageous embodiment, the time periods are integer Multiples of a basic period. The advantage here is that the control software according to the invention can be carried out according to the invention easily and quickly.

at According to an advantageous embodiment, the basic period is a timer the software of the device assigned. The advantage here is that devices whose operating and / or Control and / or regulating software is constructed such that a timer is provided, wherein in the rhythm of this predetermined Values are determined, such as current readings or the like. However, the basic period can only be changed with great effort.

at According to an advantageous embodiment, the device is a converter, an inverter, a regenerative device or a other power divider switch comprehensive device. Advantageous is that the invention applicable to various devices is when these pulse width modulated triggered semiconductor switches wherein the PWM frequency in this type of device in the prior art is constant. By means of the invention then two or more frequencies used in alternating sequence, wherein in each individual time interval the Frequency remains constant.

Important Features of the electrical appliance, that it comprises pulse-width modulated operable power electronics, the device is designed such that it can be operated with different PWM frequencies is, especially in such a fast sequence, so mixing timing, that the mixing cycle period is smaller than a thermal one Time constant. The advantage here is that the effects of mechanical stresses or their changes are reducible. In particular, the alternating load operation can be reduced and the service life thus heightened.

Significant features in the further method for operating an electrical appliance are that it comprises power electronics operated in pulse width modulation,
being dependent on the temperature, in particular Temperature of the power devices, power semiconductors or heatsink, a constant PWM frequency or a mixed-frequency PWM frequency is used.

Vorteiligerweise Thus, the optimal method is always executable, on the one hand the switching losses and then the sounds to minimize.

• – unterhalb eines ersten Temperaturwert eine erste PWM-Frequenz verwendet
• – oberhalb eines zweiten Temperaturwert eine zweite PWM-Frequenz verwendet
• – zwischen erstem und zweitem Temperaturwert eine Mischtaktung verwendet.

In an advantageous embodiment is

• - Used below a first temperature value, a first PWM frequency
• - Used above a second temperature value, a second PWM frequency
• - used a mixing cycle between the first and second temperature value.

From The advantage here is that not only the mixing timing but also constant frequencies are applicable.

at an advantageous embodiment is mixing timing of the first and second PWM frequency produced. In particular, for a first single time period the first PWM frequency and for a second single time period the second PWM frequency is used, with first and second individual time periods periodically always follow each other alternately. Is an advantage doing that, the clock ratio temperature-dependent variable is.

at an advantageous embodiment is the period of the mixing cycle greater than the PWM period of the first PWM frequency, in particular the same or greater than twice the first PWM frequency. In an advantageous embodiment the mixing timing is composed of more than two PWM frequencies. The advantage here is that a very pleasant quiet noise is reachable.

Further Advantages emerge from the subclaims.

The invention will now be explained in more detail with reference to figures:
In the 1 a method according to the invention is shown schematically. In this case, a mixing cycle in the ratio 3 to 4 is shown. In a first time interval, namely the longer, is a PWM frequency of 16 kHz and in a second time interval, namely the shorter, a PWM frequency of 8 kHz is provided.

each of the two time intervals is an integer multiple of the basic period, for example 250 μs is.

In the 2 is shown a different ratio, with each half of 8kHz and 16kHz are selected.

With These mixed clocks a low-noise operation is achieved nevertheless low power dissipation of the power semiconductor switch of the device, like Inverter, inverter regenerative unit or like.

at low frequencies are the switching losses of the power semiconductor switches least, but at these frequencies the noises are on most disturbing and uncomfortable for the human ear. Likewise, there is a noise in use generated by a constant PWM frequency, unpleasant and disturbing.

through mixed operation, the noise is more pleasant and there are less natural vibrations of the components of the device strongly stimulated.

Preferably, the individual time periods t _8kHz and t _{16kHz are} shorter than the thermal time constant of the power semiconductors. In this way, alternating load operation is avoidable and thus the service life of the power semiconductors can be extended. Because thermal shocks caused by thermal stress changes have a negative effect on the service life. In order to keep the temperature strokes so small, the individual time spans should be smaller than the thermal time constant of a layer or component of the power semiconductor switch or the chip housing of the power semiconductor switches.

In a further embodiment of the invention is changed the described mixing cycle depending on the temperature. It means that the individual time intervals dependent are made by the power semiconductor switch corresponding Temperature. The alternating load operation remains through the mixing cycle prevented. The relative ratio the individual time intervals to each other is therefore as a function of Temperature set. Thus, with increasing temperature, usually caused by increasing load, the lower frequency corresponding single time interval extended over the other single time interval.

In a further embodiment of the invention is at low temperature, which corresponds to a very low utilization, a constant high frequency, for example 16 kHz applied. Only when the temperature gets bigger, for example, as the load increases, the one described above Mixed timing activated. At very high utilization then becomes one constant low frequency, for example 4 kHz applied.

In this method, so at least three different modes are coupled, which are selected depending on the temperature. Thus are low switching losses and pleasant low noise during operation achievable.

t _16kHz

Single-time

t _8kHz

Single-time

Claims (14)

Method for operating an electrical appliance, comprising pulse-width modulated power electronics, characterized in that in a first time period, a first PWM frequency is used and in a second time period, a second PWM frequency is used, which differs from the first. Method according to at least one of the preceding Claims, characterized in that in further periods further PWM frequencies be used. Method according to at least one of the preceding Claims, characterized in that the periods of time follow one another in a repetitive sequence. Method according to at least one of the preceding Claims, characterized in that the time periods are smaller than one thermal time constant of a layer or component of a power semiconductor switch the power electronics. Method according to at least one of the preceding Claims, characterized in that the time periods are integer multiples are a reason period. Method according to at least one of the preceding Claims, characterized in that the basic period is a timer of the software of the equipment assigned. Method according to at least one of the preceding Claims, characterized in that the device is a converter, an inverter, a regenerative device or a another power divider switch is comprehensive device. Method for operating an electrical appliance, full pulse-width modulated power electronics, depending on the temperature, in particular the temperature of the power components, Power semiconductors or heat sinks, a constant PWM frequency or a mixed-frequency PWM frequency used becomes. Method according to at least one of the preceding Claims, characterized in that Below a first temperature value a first PWM frequency is used Above a second temperature value a second PWM frequency is used - between first and second Temperature value is used a mixing cycle. Method according to at least one of the preceding Claims, characterized in that mixing timing of the first and second PWM frequency will be produced, Method according to at least one of the preceding Claims, characterized in that for a first single time period the first PWM frequency and for a second one Single-time the second PWM frequency is used, with first and second individual time periods being periodic always follow each other alternately. Method according to at least one of the preceding Claims, characterized in that the period of the mixing cycle is greater than the PWM period of the first PWM frequency, in particular equal to or greater than twice the first PWM frequency. Method according to at least one of the preceding Claims, characterized in that the mixing timing of more than two PWM frequencies is composed. Electrical appliance, full pulse width modulated operable power electronics, thereby marked that the device is designed such that it is operable with different PWM frequencies, in particular in such a fast sequence, so mixing clocking that the mixing cycle period is less than a thermal time constant.