Power conversion system

• US 7,321,262 B2
• Filed: 10/07/2004
• Issued: 01/22/2008
• Est. Priority Date: 10/09/2003
• Status: Expired due to Fees

• Current Assignee: Bang & Olufsen ICEpower A/S (Bang & Olufsen A/S)
• Original Assignee: Bang & Olufsen ICEpower A/S (Bang & Olufsen A/S)
• Inventors: Fenger, Lars Michael, Nielsen, Karsten
• Primary Examiner(s): Nguyen; Patricia
• Application Number:
  US10/570,324
• Publication Number:
  US 20070109044A1
• Time in Patent Office: 1,202 Days
• Field of Search: 330/10, 330/251, 330/207.A
• US Class Current: 330/10
• CPC Class Codes: H03F 1/305 in case of switching on or off of a power supply
• CPC Class Codes: H03F 2200/03 the amplifier being designed for audio applications
• CPC Class Codes: H03F 2200/351 Pulse width modulation being used in an amplifying circuit
• CPC Class Codes: H03F 3/217 Class D power amplifiers; Switching amplifiers
• CPC Class Codes: H03F 3/68 Combinations of amplifiers, e.g. multi-channel amplifiers for stereophonics power amplifiers using a combination of several semiconductor amplifiers H03F3/211; combinations of amplifiers using coupling networks with distributed constants H03F3/602

Abstract

A power conversion system comprising at least one Pulse Modulated Amplifier (1), including a pulse modulator for generating a pulse modulated signal based on a reference input (v_i), a switching power stage arranged to amplify the pulse modulated signal, and a control system arranged to compensate for power supply voltage variations, and a voltage supply (2) providing drive voltage (V_s) to each amplifier, wherein said voltage supply (2) is provided with said input reference (v_i), and arranged to provide a first drive voltage component (V_s) tracking an amplified absolute value of the input reference (v_i). Pulse area modulation according to the invention will result in improved efficiency and at the same time ensure lower levels of EMI, as the mean amplitude of the PAM signal is lowered.

Claims

1. A power conversion system comprising:

at least one Pulse Modulated Amplifier (PMA) (1), including a pulse modulator for generating a pulse modulated signal (v_pulse) based on a reference input (v_i), a switching power stage arranged to amplify the pulse modulated signal, and a control system arranged to compensate for power supply voltage variations, and

a voltage supply providing a drive voltage (V_s, V_d) to each amplifier,

wherein

said voltage supply is provided with said input reference (v_i), and arranged to provide a first drive voltage component (V_d) tracking an amplified absolute value of the input reference (v_i).

2. A power conversion according to claim 1, wherein the pulse modulator is a pulse width modulator.

3. A power conversion system according to claim 2, wherein the pulse modulator is a Controlled Oscillating Modulator (COM).

4. A power conversion according to claim 2, wherein the pulse modulator is a digital PCM-PWM modulator and where the control system is a Pulse Edge Delay Error Correction (PEDEC) control system arranged to obtain a high PSRR.

5. A power conversion system according to claim 1, wherein the first drive voltage component (V_d) is equal to k*|v_i|+Δ

, where k is a constant and Δ

is a fixed headroom.

6. A power conversion system according to claim 5, wherein the voltage supply is arranged in such a way that the headroom Δ

increases, when the power supply has to deliver a drive voltage (V_d) with a negative

$\frac{d<br><br>V}{d<br><br>t}.$

7. A power conversion system according to claim 1, wherein the first drive voltage component (V_d) is controlled by a peak-detection of the output signal (V_o) of the PMA, said peak detection preferably generated by volume control information provided to the voltage supply.

8. A power conversion system according to claim 1, wherein the drive voltage (V_d) has a maximum and minimum

$\frac{d}{}$

V ⅆ

t

value of a music signal controlled by the input reference (v_i).

9. A power conversion system according to claim 1, wherein the voltage supply further is arranged to deliver a second drive voltage component (V_s) equal to the inverse of the first component (V_d).

10. A power conversion system according to claim 9, wherein the first and second drive voltage components (V_s, V_d) have a maximum and minimum

$\frac{d}{}$

V ⅆ

t

value of a music signal controlled by the input reference (v_i).

11. A power conversion system according to claim 1, wherein the voltage supply comprises current sink means.

12. A power conversion system according to claim 1, wherein the input reference (v_i) is superimposed on the drive voltage (V_s, V_d) which is connected to the amplifier(s).

13. A power conversion system according to claim 1, further comprising a low pass filter connected to the switching stage.

14. A power conversion system according to claim 1, directly connected to an electro-dynamic transducer.

15. A power conversion system according to claim 1, where each Pulse modulated amplifier is implemented as a Class D power amplifier.