Method and device for inductive transmission of electric power to a plurality of mobile consumers

• US 6,462,432 B1
• Filed: 07/31/2000
• Issued: 10/08/2002
• Est. Priority Date: 08/18/1997
• Status: Expired due to Term

• Current Assignee: Alstom Anlagen - Und Automatisierungstechnik GmbH
• Original Assignee: Alstom Anlagen- und Automatisierungstechnik GmbH
• Inventors: Kaus, Eberhard, Lindig, Erik, Salama, Samir, Seelig, Anton
• Primary Examiner(s): FLEMING, FRITZ M
• Application Number:
  US09/403,044
• Time in Patent Office: 799 Days
• Field of Search: 307/17, 307/104, 307/31-35
• US Class Current: 307/33
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/40 using two or more transmitting or receiving devices H02J50/50 takes precedence

Abstract

What follows is a description of a method and device for the inductive transmission of electric power from a medium-frequency source with a frequency of (f_M) to one or more mobile consumers which are inductively coupled to the transmission line via an extended transmission line.

Claims

1. A method for inductive transmission of electric power from a medium-frequency source at a frequency (f_M) to one or more mobile consumers via an extended transmission line and via inductive pickups (I_AX, I_AY), assigned to the mobile consumers, the mobile consumers being connected to buffer memory, the method comprising the steps of;

providing downstream converter-actuators for adjusting the power (P_LX, P_LY) that is picked up from the transmission line and delivering said adjusted power to the buffer memory;

supplying the transmission line from a current source with a medium-frequency current (IL) that is constant in its effective value during power transmission;

adjusting, infinitely variably, the output voltage (UL) of the medium-frequency source, within a maximum adjusting time (T_S) which lasts for only a few half-periods of the medium-frequency (f_M), to the value that corresponds to the total variable power picked up from the transmission line; and

adjusting, infinitely variably and with a limited rate of change, with the converter-actuator connected between the buffer memory and the inductive power pickup (IA) of each power consumer, a power (P_L), picked up from the transmission line and delivered to the buffer memory, within an adjusting time (T_A), which is longer than the adjusting time (T_S) of the medium-frequency source.

2. The method of claim 1, further comprising the step of:

providing a signal (SB) that controls the converter-actuators, the signal containing;

information on said infinitely variable adjustment of the power (P_L) picked up by the inductive pickup (IA) from the transmission line and delivered to the buffer memory, and information on the rate of change of this power and thus also the information for realizing the adjusting time (T_A) of the converter-actuator.

3. The method of claim 2, further comprising the steps of:

regulating the output voltage (UA) of the buffer memory that is delivered to the mobile consumers to a predetermined desired value (U_ASOLL); and

determining the information contained in the control signal (SB) of the converter-actuator, for adjusting the power (P_L) picked up from the transmission line, along with its rate of change by the power (P_V) picked up from the consumer and by the dimensioning of the timing of this regulation.

4. The method of claim 1, further comprising the steps of:

maintaining the effective value of the current (I_L) supplied to the transmission line by the medium-frequency source at a constant value during the power transmission to the mobile systems, and in time ranges in which no power or only little power compared with the total power that can be transmitted is being transmitted; and

controlling infinitely variably this effective value at a rate of change that is substantially below the allowable rate of change in the power that can be picked up from the transmission line.

5. The method of claim 4, further comprising the step of;

regulating the effective value of the medium-frequency current (I_L) supplied to the transmission line to a predetermined desired value (I_LSOLL).

6. A device for inductive transmission of electric power from a medium-frequency source at a frequency (f_M) to one or more mobile consumers via an extended transmission line, comprising:

buffer memory connected to said one or more mobile consumers;

inductive pickup (I_AX, I_AY) assigned to said one or more mobile consumers; and

downstream converter-actuators for adjusting the power (P_LX, P_LY) that is picked up from the transmission line and delivered to said buffer memory, wherein the medium frequency source has a maximum adjusting time (T_S) of its output signal that is less than the adjusting time (T_A) of the power picked up at the consumer.

7. The device of claim 6, wherein said transmission is located between the medium-frequency source and the mobile consumer, and wherein said mobile consumer is embodied as a series oscillation circuit for this medium frequency.

8. The device of claim 6, further comprising:

a low frequency/medium frequency converter with an intermediate circuit direct voltage (U_G) buffer-stored by a capacitor (C_G) and an inverter (W), formed of controllable power semiconductors (T1, T2, T3, T4) and controlled by a frequency generator with a constant medium frequency (f_M), for generating a pulsed AC output voltage (u_W); and

a coupling network connected to the AC output voltage (u_W) of said converter and which has a series oscillating circuit formed by an inductive resistor (L₁) and capacitor (C₁) , whose resonant frequency 1/(2,π

L₁ C₁) matches the frequency (f_M) of said converter, and wherein the terminals of said capacitor (C₁) are the outputs of the medium-frequency source.

9. The device of claim 8, wherein said inductive resistor (L₁) and said capacitor (C₁) of said coupling network are dimensioned for attaining a transmission rated power (P_N) in accordance with the equation (L₁/C₁)=U_IN²/P_N where U_IN, is the effective rated voltage of the fundamental oscillation of the pulsed output voltage (u_W) of said low-frequency/medium frequency converter.

10. The device of claim 8, further comprising:

a transformer (TR) connected between said capacitor (C₁) and said transmission line, having a transformation ratio (w₁/w₂); and

substitute resistors (R_XN) coupled into said transmission line said inductive pickups (I_AX) when the rated power is picked up, wherein said transformer transforms the sum of said substitute resistors into a value (Σ

R_XN) that is effective at said capacitor (C₁) and that is equal to the oscillation resistance (L₁/C₁) of said coupling network.

11. The device of claim 6, further comprising:

a pulse width modulation stage (PMI), wherein turning on and off of one of said controllable power semiconductors (T1, T2, T3, T4) of said low-frequency/medium frequency converter is effected by said pulse width modulation stage so that a pulsed AC output voltage (U_W) of variable pulse width (T_D) is created, and a signal (S_D) for adjusting the pulse width (T_D) and thus an effective value (U₁) of the fundamental oscillation of said AC output voltage (u_W) is delivered to said pulse width modulation stage.

12. The device of claim 6, further comprising:

a regulator (KOR); and

a pulse width modulation stage (PMI), wherein the desired value (I_LSOLL) of the medium-frequency current supplied to said transmission line and the measured value (I_LM) of the medium-frequency current actually supplied are delivered, and wherein said regulator (KOR) forms one component (SDR) of said input signal (SD) of a pulse width stage (PMI) which signal adjusts said variable pulse width (T_D).

13. The device of claim 6, further comprising:

a capacitor (C_L); and

an inductive resistor (L_L), wherein said capacitor (C_L) is connected in series with said transmission line, and said capacitor (C_L) is dimensioned as to its capacitance such that it compensates for the inductive voltage drop (U_LL) that occurs at the inductive resistor (L_L) of said transmission line.

14. The device of claim 6, further comprising:

a second pulse width modulation stage (PM2); and

a controllable power semiconductor, wherein said second pulsed width stage (PM2) converts an input signal (EM) applied to it into a pulsed signal (SB) delivered to said controllable power semiconductor, in such a way that the ratio between the OFF time (T_W) of said controllable power semiconductor and the cycle time (T_Z) is proportional to the value of the input signal (EM), and wherein the cycle time (T_Z) is on the order of magnitude of one-half of the period length (T_M/2) of said medium frequency (f_M).

15. The device of claim 14, further comprising:

a voltage regulator stage (RU); and

a buffer capacitor (C_P), wherein said voltage regulator regulates the output voltage (UA) of said buffer capacitor (C_P) to a desired value (U_ASOLL), and delivers a signal component (EMU) of the input signal (EM) to said second pulse width modulation stage (PM2), and wherein the rate of change of said signal component (EMU) is dimensioned by the capacitance of said buffer capacitor (C_P) and the transmission function (FU) of said voltage regulator stage (RU), such that in the event of a sudden change in the output current (IA) of said buffer capacitor (C_P), the signal component (EMU) attains its new value only after the adjusting time (T_A) of the converter-actuator, which is longer than the adjusting time (T_S) of said medium-frequency source.

16. The device of claim 14, further comprising:

an active damping stage (AD); and

an oscillatable partial circuit comprising a parallel oscillator circuit (L_H″

, C_K) of an inductive pickup, a rectifier (G2) and an inductive resistor (L_Z) of an intermediate circuit, wherein said active damping stage (AD) delivers a further signal component (EMD) of said input signal (EM) to said second pulse width modulation stage (PM2) for damping natural oscillation of the intermediate circuit current (I_Z) in said oscillatable partial circuit.

17. The device of claim 14, further comprising:

a current imposition stage (SA) having a delay stage (VI), wherein said current imposition stage (SA) delivers a signal component (EMA) of said signal (EM) to said second pulse width modulation stage (PM2), said signal component, in a steady state condition, is proportional to the output current (IA) and is dimensioned such that via said second pulse width modulation stage (PM2) it adjusts a ratio between the OFF time (T_W) of said controlled power semiconductor and a cycle time (T_Z) at which the power (P_L) picked up from said transmission line nearly matches the consumer power (P_V), and it transmits sudden changes in the output current (IA) to said signal component (EMA) with a delay, so that the adjusting time (T_A) of said converter-actuator, which lasts longer than the adjusting time (T_S) of said medium-frequency source, is adhered to.

18. The device of claim 14, further comprising:

a rectifier (G2); and

a synchronizing stage (SS) generated by a synchronizing signal (SY) from one of;

said medium-frequency input current (WE) and said output voltage (UE) of said converter-actuator, said synchronizing signal (SY) being delivered to said second pulse width modulation stage (PM2) and varies the formation of an output signal (SB) of a pulse width modulation stage, in such a way that the cycle time (T_Z) of said output signal (SB) precisely matches the duration of one-half of the period length (T_M/2) of said medium frequency (f_M), and the OFF time of said controllable power semiconductor (TS) is located approximately half before and half after the peak value of the output voltage (u_B) of said rectifier (G2).