DE19625868C1 - Method of controlling heating device for electric trams to maintain room temp. over defined period - Google Patents

Abstract

The method involves computing the required electrical heating energy to maintain a defined room temp. over a given period from the vehicle characteristics and the external temp. The vehicle contains at least one electric motor which can be switched over to generate electricity. The current electrical heating energy is derived from the generator braking and/or the primary power source. The current heating energy is applied by the electric drive motor and/or drawn from the primary source, the current heating energy is subtracted from the required energy and the process repeated until the required energy has been supplied or the end of the time interval reached.

Description

The invention relates to a method for controlling at least of an electric heater in a vehicle with at least least an electric traction motor by a primary Power source is supplied and switchable as a generator is.

Such electric heaters are used for heating Passenger compartments in electrically powered vehicles, e.g. B. Trams. The supply voltage of the vehicles is here also used for heating. The heating is on while driving switched on especially in the braking phase (clocked loading driven) to the regenerated energy of the drive for heating to use (DE 28 35 120 C2). In this case, the Voltage can be raised. When the vehicle is at a standstill the heating energy is taken from the network. Depending on the ver Division of the entry points (substations) in the network and the Network loads from other vehicles are large network chips fluctuations in voltage possible and permissible. This leads to a The heating switch-on time depends on the outside temperature to an irregular energy supply. The heating must half be designed for a certain voltage to the Switch-on time depending on this voltage control of the outside temperature. Because of the quadra This leads to the table dependence of energy on voltage known control method to a highly fluctuating interior temperature. In networks with a high voltage drop, the Heating times therefore correspond to extensive measurements be interpreted accordingly.

The object of the invention is therefore a method of to create the kind mentioned above, even with a strong network  voltage fluctuations a largely constant internal temperature door of the heated room.

The object is achieved by the features of the An spell 1 solved. Advantageous embodiments of the invention are described in the further claims.

The method of claim 1 is used to control at least of an electric heater in a vehicle with at least least an electric traction motor by a primary Power source is supplied and switchable as a generator is. For this, the vehicle properties become dependent of the outside temperature for a specifiable room temperature temperature necessary within a predefinable time interval electrical heating energy calculated. Furthermore, the electrical values of regenerative braking and / or Primary energy source is the current electrical heating energy calculates, whereby the applied by the electric traction motor and / or current from the primary energy source electrical heating energy from that in the specified time interval necessary electrical heating energy is deducted. This The process is repeated until the necessary electri cal heating energy applied or the end of the time interval is reached.

The inventive method is for all types of elek trically driven vehicles (diesel-electric drive, Fuel cell or battery as primary energy source, driving wire feed). Heaters that are ren are controlled according to claim 1, do not require mixing chambers for mixing the heated air with the outside air and no isolation chambers that cool the heated air prevent. This allows heaters according to the Invention be operated according to the method, corresponding to the design be simple and easy to set up.  

The method of claim 1 is also for heating suitable from different interiors. So z. B. like this probably passenger compartments as well as driver's compartments of vehicles be heated. Also heating electrical interiors Components to prevent condensation on the component len is possible.

In the method according to claim 1, the heaters are ge clocked operated. This operating mode can be used in driving mode (hereinafter referred to as pulsed normal heating operation) also for quick warm-up of the vehicle (clocked pre heating mode) can be selected.

Should the vehicle be parked for a longer period in the cold months cooling below a predefinable minimum temperature be prevented, then it is particularly advantageous To operate heaters according to a method according to claim 2 (hereinafter referred to as cyclical keep-warm mode). The heating devices are switched on at different times. Man thereby achieves a uniform current load without briefly a high current flows in total. With the procedure according to claim 2 is of course a cyclic Preheating operation for quick warming up of the vehicle possible.

The clocked normal heating operation defined by claim 1 ensures z. B. for Central European weather conditions nisse i. a. even with strong network fluctuations a largely constant inside temperature of the heated room. To also at extremely low outside temperatures and strong network fluctuations a constant internal temperature of the heated Ensuring space is a method according to claim 3 particularly well suited.

The invention and further advantageous refinements that The following claims are the subject of further claims based on diagrams and characteristic curves in the drawing explained. Show it:  

Fig. 1 flow diagram for the process according to claims 1 to 3,

Fig. 2 characteristic for the Normalheizbetrieb,

Fig. 3 Distribution of heating energy to be supplied to the base clock,

Fig. 4 timing diagram for the cyclic switching on of the heating circuits,

Fig. 5 timing diagram of the energy absorption under cyclic heating operation,

Fig. 6 switch-on conditions for normal heating and clocked preheating at the beginning of the basic cycle

Fig. 7 switch-on conditions of the heating circuits during the basic clock cycle in clocked heating mode.

The heating control is on a tram with the Signals "pantograph above, battery on and mains voltage available "switched on.

When the vehicle is disarmed (vehicle upgraded means: battery is in and driver key is inserted; vehicle is disarmed means that battery is in and driver key is not inserted), the heating control system runs through the keep-warm program. If the temperature in the vehicle has dropped sharply when switched on (T _inside <T _{W off} ), heating is carried out in cyclical operation until the inside temperature T _{W off is} reached.

If the driver's cab is manned, it depends on the journey directional switches either in the cyclical or in the ge clocked preheating mode switched.

If the direction switch is not in the "forward" position, the control system runs through the cyclic pre-heating mode. The vehicle is preheated to the target internal temperature T _V. The heaters are then switched off as long as the internal temperature is within the switch-off hysteresis.

If the direction of travel switch is in the "forward" position, then the cycle is preheated. This takes place up to a certain internal temperature T _V.

The preheating mode is replaced by the clocked normal heating mode via this temperature limit. In the normal heating program, the inside temperature value reached during preheating should be kept as constant as possible. If the internal temperature reaches the limit value T _N , the clocked normal heating operation is switched off. Switching on only takes place again when the internal temperature has dropped to the lower hysteresis temperature.

The clocked operation and the cyclic operation are defined as follows:
In pulsed operation, the heaters are preferably fed by the electrical braking energy. The control system checks in a certain period of time (basic cycle) whether the system is braking and then switches on the heating. If the heating energy cannot be applied by the brake within the basic cycle, the heating system absorbs energy from the network. This operating mode is used when driving, as braking energy can then be expected.

Cyclic operation is used when the tram is stationary for a long time, e.g. B. in the tram depot. In cyclical operation, the heating contactor remains switched on for the specified time t _wine / t _vein . The contactors are switched on by the time t _Wvers / t _Vvers offset. A constant current load is achieved over time. In this way it is prevented that all heaters heat at the same time and thus briefly a high current flows in total.

When a driver's cab is dismantled, the heating switches on again in the keep warm mode.

The temperature detection necessary for the control of the heaters takes place via several temperature transmitters, of which at least two are preferably installed in each interior and two on the outside of the vehicle. The temperature transmitters are queried by the central control unit. The central control unit converts the read values into a fixed data format and checks them for overflow and wire break. In the event of an error, substitute values are formed (e.g. valid values of the other sensors). For further processing in the software program, a reference value for inside temperature T _inside and outside temperature T _{outside is formed} as the average of the read values.

If the switch-on condition for normal heating is fulfilled, ie T _{V off} <T _inside <T _{N off} , the normal heating program is run.

In normal heating mode, heating is carried out according to the temperature-performance curve shown in FIG. 2. The output specification remains constant during the calculation of the heating energy. On the other hand, the switch-on time of the heating circuits is variable due to the voltage included in the calculation. The following describes how the heating energy (or the sizes of the heating calculation) required to heat the vehicle to its solitary temperature is calculated.

The heating energy required is calculated for one basic cycle t _basic. . The basic cycle of the heating calculation results from the average distance between stops and the average travel speed. It must either be redefined for each location or determined using a self-learning program. The variable t _rest is the remaining time within the basic cycle. It is the beginning of the basic clock cycle to the set value t _basic set. The remaining time is counted down by one per time interval (e.g. per second). If the remaining time has expired, the specified value is loaded again.

The heating energy required depends on the average heating output and the basic cycle time. The mean Heizlei performance is plotted in the characteristic curve ( Fig. 2) depending on the outside temperature. If the outside temperature is below the switch-off temperature T _N , heating energy must be supplied to the vehicle. The lower the outside temperature, the more energy has to be supplied. If the outside temperature is lower than the minimum outside temperature, heating is carried out with maximum heating power, since the maximum duty cycle of the heaters must not be exceeded. If the outside temperature is above the break point temperature, heating is carried out with a constant minimum heating power P _min up to the switch-off point. This is to prevent the heating contactors from being activated too short due to very low power values.

In order to keep the characteristic curve independent of the basic cycle time t _Grund , the average heating output was plotted against the outside temperature. This output, multiplied by the basic _{cycle time, is stored} in the central control unit at the beginning of each basic cycle as energy to be _supplied . In the following only energy values are used for the calculation.

At the beginning of the basic cycle, it is not yet known when the next network brake (regenerative braking with feedback to the primary energy source) will take place. Therefore, the time t _ZW is also determined in seconds at the beginning of the basic _cycle , which must be heated if there is no braking within this basic cycle. In this case the heating must be operated with mains power. This so-called forced heating is used when the remaining time t _rest within the basic cycle has elapsed to the calculated time value and the calculated energy has not yet been supplied to the heaters.

If there is a braking phase during the basic cycle ( Fig. 7) and the energy to be supplied (determined from the characteristic curve) has a positive value, the heating is switched on during braking. To determine the energy consumed, use the formula:

E _spent = U _medium ² / R × t _heating .

The resistance of the heating elements is constant and can be seen from the general heating device data. The voltage is recorded 10 times per second and the mean value is formed from it. For every second t _{heating of} the braking phase, the mean value of the voltage from the previous second is used for the calculation.

The aim of the timed heating control is to use all electrical grid braking phases for heating and thus to use the entire energy to be supplied sparingly. If the entire energy is used during braking in a basic cycle, then no forced heating is necessary in this cycle ( Fig. 3 above). In the next cycle, the energy to be supplied is determined again using the characteristic curve (E _to = E _{characteristic} ).

In network braking phases that last less than 3 s, the Software braking time for evaluation in the heating control Extension extended to 3 s. This is a minimum switch-on time of the heaters guaranteed. Additionally, this way also the switching frequency of the heating contactors within the Basic clock limited. This measure is particularly justified due to the fact that occurs especially in trams "stop and go" traffic, which is a frequent braking of the driver brings with it.  

If the braking phase is not sufficient to supply the heaters with sufficient energy, then the remaining energy must be supplied in forced heating mode ( Fig. 3 middle and below).

Forced heating begins when the remaining time t _{rest is} less than or equal to the calculated switch-on time. To do this, calculate the required switch-on time, which is derived from the remaining heating energy and a reference voltage that is fixed for the time of the forced heating according to the formula

t _ZW = E _remainder × R / U _Zw ²

can be determined.

The voltage U _ZW is equal to the average voltage U _medium at the beginning of the forced heating. The energy E _rest is obtained from the difference between the energy to be supplied and the energy consumed;

E _rest = E _to -E _spent. .

The energy consumed is like heating with braking current, calculated depending on the current mean voltage.

At the bottom of the clock, the difference between the determined and ge total energy consumed:

E _rest = E _{characteristic} -E _spent .

The result can have both negative and positive values because the underlying voltage U _{Zw has} a fixed value when calculating the forced cycle time and the current voltage value can deviate therefrom. The forced heating time determined in this way therefore does not exactly correspond to the time that would have to be heated in order to convert all of the energy to be supplied into heating energy within the basic cycle. The difference is taken over in the next cycle and added to the characteristic value. This energy thus represents the energy to be supplied in the next basic cycle:

E _to = E _{characteristic} + E _rest .

The clocked preheating mode ( Fig. 1) is switched on in the upgraded vehicle and with the direction switch in the forward position. It is based on the same control principles as normal heating operation.

The difference between the two heating programs is the determination of the required heating energy. In preheating mode, the vehicle should be heated to the required internal temperature T _V in the shortest possible time. It is preheated regardless of the power-outside temperature characteristic. The heaters are controlled depending on the specified energy E _Vein . This energy can be pre-set by the operator and must not exceed the maximum energy specified in the heating calculation. Within the basic clock cycle, this energy is supplied to the heaters with the preferred use of braking energy and forced heating. The basic cycle is processed as in normal heating.

The cyclical preheating mode ( Fig. 1) is used to heat upgraded, parked vehicles (direction switch ter in zero position). The heating is switched on up to the upper temperature limit T _V. Only the interior temperature is used as a comparison value. If the limit value T _{V off} is exceeded, the cyclic preheating mode is switched off. Thereafter, the device is only switched on again when the temperature has dropped below the lower hysteresis temperature.

The heating circuits are switched on depending on the time values set by the operator for duty cycle t _{V on} and displacement time t _{V vers} . These values are specified individually for each heating circuit ( Fig. 4).

The time t _V indicates how long the heating circuits are switched on. The ratio of the duty cycle to the heating break should be less than the maximum switch-on time per heating cycle specified in the heating calculation so that the heaters are not overloaded. The offset time t _{V vers} is the time that lies between the activation of two heating circuits that follow one another in the connection sequence. If you select the shifting time for all heating circuits equal to the switch-on time, the switch-on and switch-off processes of two heating circuits coincide and the current consumption becomes more even.

When designing the individual switch-on and offset times must be taken to ensure that the relationship from Heating phase and heating break of a heating circuit less than or equal to is the ratio of the maximum switch-on time to the minimum pause time defined for the heating circuits.

This ratio can be calculated using the following formulas:

With the help of the duty cycle and the transfer time you can Set how quickly the vehicle should be heated up. If you choose a short transfer time and a large on switching duration, then the vehicle is warmed up quickly, whereby a high current was absorbed by the heating circuits becomes. Such a setting is for the clocked preheating operation recommended.

When selecting the transfer times, you should always make sure that the total energy consumption of the connected heating circuits is constant over time. From Fig. 5 it can be seen that a constant energy consumption is guaranteed by simultaneous activation of two heating circuits.

The keep-warm mode is cyclical and is run through in parked, not upgraded vehicles. The heating circuits are switched on cyclically in accordance with the preheating mode ( Fig. 4). In this case, separate values for the switch-off temperature T _{W off} and for the switch-on time t _{W on} and displacement time T _{W vers of} the heating circuits are set by the user for the keeping-warm mode.

We recommend a shorter switch-on time and a longer one Dislocation time per heating circuit to be selected as in preheating mode len, so that the total power consumption of the heating circuits is lower and is more even.

In the described embodiment, the ver drive to control at least one electric heater The following parameters are used.

The following are available as adjustable values:
t _W on duty cycle in warm operation
t _W offset time in warm operation
T _{W from the} internal temperature value at which the keep-warm mode is switched off
E _{V is an} energy value for preheating
t _{V a} duty cycle in cyclic preheating mode
t _V offset time for cyclic preheating
T _{V from the} internal temperature value at which the cyclical preheating mode is switched off or the clocked preheating mode is replaced by the normal heating mode
T _{N from the} indoor temperature value at which normal heating operation is switched off
t _Basic duration of a basic measure
t _{after L} fan run-on time
T _amine Setting point for the minimum outside temperature
T _amax setting point for the maximum outside temperature (= switch-off temperature)

The following dynamic values result:
T _inside Determined value for the interior temperature
T _outside Determined value for the outside temperature
U _mean mean of the voltage, e.g. B. formed from the ten voltage values of the last time interval (e.g. second)
U _Zw Voltage that is used to calculate the heating time for forced heating
P _kennl Average heating power, which is determined at the beginning of the basic cycle from the power-outside temperature characteristic
E _char energy resulting from the mean power level (determined from characteristic) and the basic clock time is calculated (E = P _{char char} * t _reason)
E consumed energy within a basic _cycle
E results _to be supplied to energy _char from the sum of E and the non-consumable th last base clock residual energy
E _rest energy, which results from the difference between the supply of energy and the energy consumed
t _rest remaining time within a basic clock
t _heating heating time for the calculation of the energy consumed (clock = 1 s)
t _Zw time that must be heated at the end of a basic cycle in order to completely heat the specified energy (forced heating)

The following physical data are available as fixed values:
R resistance of the heaters
t _{a max} / t _{pause min} ratio of the maximum switch-on time and minimum _{pause time} according to the heating calculation
T _Kink Kink point temperature from which the minimum heating output is used
P _min minimum heating output in the lower kink area of the characteristic
P _max Maximum heating output with minimum outside temperature

The described embodiment of the invention The process relates to forced air heaters. That explained However, the method is just as good for controlling Fresh air heaters can be used. In this case, additional the internal and the injection temperature are also taken into account will.

Claims (8)

1. A method for controlling at least one electric heater in a vehicle with at least one electric traction motor, which is supplied by a primary energy source and which is switchable as a generator, the method comprising the following steps:

• the electrical heating energy required for a predeterminable room temperature within a predefinable time interval is calculated from the vehicle properties, depending on the outside temperature,
• - The current electrical heating energy is calculated from the electrical values (I, U) of the regenerative braking and / or the primary energy source
• - The current electrical heating energy is applied by the electric traction motor and / or taken from the primary energy source, and
• - the current electrical heating energy is subtracted from the electrical heating energy required in the given time interval,
• - This process is repeated until the necessary agile electrical heating energy is applied or the end of the time interval is reached.

2. The method according to claim 1, characterized, that with a long standstill of the vehicle at little at least two heaters in a definable time Sequence individually or overlapping from the primary energy source. 3. The method according to claim 1, characterized, that the value of a lack of necessary electrical heating energy is transferred to the next time interval.   4. The method according to claim 1, characterized, that as an electrical value for calculating the current electrical heating energy for regenerative braking for feedback to the primary energy source Voltage (U) and / or the voltage (U) of the primary energy source serves. 5. The method according to claim 1, characterized, that as an electrical value for calculating the current electrical heating energy in regenerative braking current (I) flowing in the electric heater and / or from the primary energy source to the electric heater flowing current (I) is used. 6. The method according to claim 4, characterized, that the current electrical heating energy according to the relationship E ∝ U² / R is calculated. 7. The method according to claim 4 or 5, characterized, that the current electrical heating energy according to the relationship E ∝ U · is calculated. 8. The method according to claim 5, characterized, that the current electrical heating energy according to the relationship E ∝ R · I² is calculated.